Monday, 31 December 2012

Insulin makes you fat - Final nail in the coffin?

This could be it, the final nail in the coffin. Really!!!

PPAR gamma 2 prevents lipotoxicity by controlling adipose tissue expandability and peripheral lipid metabolism.

Back in this post  I made the point that the transcription factor PPAR(gamma) was critical for the development of obesity. And that this is probably how insulin makes you fat, because ultimately insulin stimulates PPAR(gamma) in adipose tissue.

PPAR(gamma) exists with 2 isoforms,  PPARg1 is expressed in alot of different tissues, but PPARg2 is primarily expressed in adipose tissue. Theres a funny study from back in 1997 that looked at different ways you can activate PPARg, we know that thiazolidinediones activate PPARg but this study from 1997 shows activation by non-ligand means. This occurs at the N-terminus, whatever the fuck that is.

But anyway...

This is gonna get a bit technical now, hopefully you can keep up,

The below graph shows how strongly each isoform of PPARg is activated when you poke its N-terminus.

As you can see in the graph, PPARg2 shoots up like a rocket when you activate its N-terminus.

Next we activate the N-terminus with and without insulin. We use something called GAL4 to activate the N-terminus, and at the same time we incubate the cells with and without 10nM insulin.

Graph B is our focus. This graph shows that insulin alone cannot activate PPARg2, as evidenced by "Empty Gal 4" column. But look at the very end, when you have both GAL4 and insulin, PPARg2 goes to the moon.

So basically, this study shows that activation of PPARg2 is dependent on something poking its N-terminus, but if you have insulin when this happens, the affects are multiplied.

Interesting bits next, I promise

We go back to the study I linked at the top of this post, its title is quite revealing, remove the lipotoxicity part and you have "PPARg2 controls adipose tissue expandability". I.E. PPARg2 controls how fat your ass gets.

Here the researchers generated ob/ob mice ( leptin deficient mice ) but also without PPARg2. Now, we know that ob/ob get massively obese and eat everything in site, they also refuse to move. Next picture shows the characteristics of ob/ob mice that also dont have PPARg2.....

Look at the bodyweight and food consumption graphs, the double knockout leptin/PPARg2 mice eat just as much as the ob/ob mice, but stay as lean as the wild type mice!.  Imagine that.....  ( Note there was a slight increase in weight in the female double knockout mice, but the male double knockout mice weighed the same as controls. Not surprisingly really as we know that sex hormones play an important part in bodyfat status. )

Next lets check out this quote....

Furthermore insulin resistance in adipose tissue was demonstrated by the extremely low levels of glucose transporter4 (GLUT4) protein in POKO adipose tissue when compared with GLUT4 levels in adipose tissue from ob/ob mice

This ties in with the GLUT4 and how it influences obesity. With this data in mind, my model for obesity goes like this......

insulin acts on adipocyte -> multiplied PPARg2 activity -> increased GLUT4 expression -> adipocyte hyperplasia.


  •  Obesity is dependent on PPARg2 activity, not food intake ( there is evidence you can still hypertrophy adipocytes without PPARg2, but you cannot hyperplasia adipocytes ).
  •  Insulin alone does not increase PPARg2
  •  Insulin along with something that activates N-termnius in PPARg2 greatly increases PPARg2 activity.

P.S. there is one final interesting comment in the paper that caught my eye...

However POKO had similar total locomotor activity compared with ob/ob mice

POKO are the double knockout mice, and despite them weighing the same as controls, they had reduced urge to move like ob/ob mice. This fits in with something I saw in another paper about how PPARg might control urge to move. As strange as that sounds.

I hope to make a short followup post that suggests laziness is a response to be obesity, and not a cause of obesity.

Friday, 28 December 2012

Sipping glucose vs Bolus dose - Jenkins study

I got this oldish study from Donny who comments at hyperlipid.

In this study they got together 9 healthy males and asked them to drink a glucose drink containing 50g, but they varied the timecourse over which they could drink it. In the bolus dose test, the subjects drank the whole 50g in 5 minutes, in the sipping test, they sipped the glucose drink at a constant rate of 3.5g per 15 minutes. ( so the entire drink was consumed in 3.5 hrs )

Keep in mind, in both tests, the glycemic index is the same, because the form of the glucose is the same, but what changes is the glycemic load, I.E., in the amount of glucose entering the portal vein. ( technically its called the mass flow rate )

Here is the blood glucose graph.....

Not surprisingly, the bolus dose results in significantly higher maximum blood glucose concentrations. The area under curve ( AUC ) is a measure of the total number of glucose molecules entering circulation. Much to my shock, the total AUC for both the sipping and bolus are approximately the same indicating that in both cases, a similar amount of total glucose entered circulation. Remember, it is the job of the liver to extract glucose from the portal vein and convert it to glycogen/fat. Glucose that is harvested by the liver from the portal vein obviously does not hit circulation and so does not affect blood sugar.

So with the bolus test, we can say that unharvested glucose ended up accumulating in circulation. Once the glucose is in the circulation it needs to be disposed of the in peripheral, AKA, skeletal muscle and........ adipose tissue. To do that, we need insulin.

The higher the blood glucose concentration, the more insulin we need to "shove" that glucose into the peripheral.

So you would expect the total amount of insulin ( AUC ) secreted to be higher in the bolus test, wouldnt you? And indeed, thats exactly what we find......

No need for annotations here, we all know which curve belongs to which group. Calculated values for AUC appear in the following table.....

Now here comes the punchline, despite a similar amount of total glucose entering circulation in both the sipping and bolus tests, if you do the bolus test, youll secrete anywhere from 50% to 100% more insulin, just to deal with those higher blood glucose concentrations. All this may be quite obvious to some people, but this was actually news to me because I had thought that the amount of insulin secreted was dependent on the total amount of glucose molecules entering circulation, with some modifications due to insulin resistance ofcourse.

Although come to think of it, it does fit in with my personal anecdotes. For example ( without being technical anymore ) , I have long observed with my own body that the foods which most aggressively spike blood sugar are the exact same foods which are the most fattening. Fruit and honey do not cause nearly as much weight gain in me as potatoes/rice. And the latter spikes my blood sugar significantly more than the former.

Ever increasing blood glucose concentrations require ever increasing insulin concentrations to deal with them. You just have to ask yourself, at what point do those ever increasing insulin concentrations start to "permanently"  alter the structure and morphology of your adipose tissue, in a similar way that super concentrations of insulin from insulin injections cause localized lipohypertrophy.

Is it possible to cure that localized lipohypertrophy with diet and exercise?

If we could model obesity as simply small amounts of  "lipohypertrophy" occurring all over the body, then why are we assuming that obesity can also be resolved with diet and exercise?

Thursday, 27 December 2012

Obesity text from The carnivore connection

Fantastic link from The Breviary.

I just HAVE to copy/paste some of the interesting parts in the text from the obesity section,

While the causes of the obesity epidemic are complex and multifactorial, worldwide dietary trends over the last three decades, including lower protein intake as a proportion of energy, higher consumption of refined cereals, and the substitution of carbohydrate for saturated fat, have led to substantial increases in average dietary glycemic load.

Wait, I thought we were eating too much fat these days?

In a predominantly overweight and sedentary population, refined carbohydrates may cause greater metabolic damage than saturated fat 

WTF? Thats pure heresy. Everyone knows saturated fat KILLS.

 The Protein Leverage hypothesis proposes that animals will overeat carbohydrate and fat in an effort to achieve a specific protein target.

OK this is true, as I posted on before, low-protein diets increase AgRP, an orexigenic neuropeptide.

Diets that increase postprandial hyperglycemia and hyperinsulinemia have been shown to promote carbohydrate oxidation at the expense of fat oxidation, an effect that may be conducive to increased adiposity 

Yeh, but I know people who have lost weight on the potato diet.  NUFF SAID?

Long-term studies in animal models also show that high GI starch diets promote weight gain, visceral adiposity, and higher levels of lipogenic enzymes compared with isoenergetic, macronutrient-controlled low-GI starch diets

See above.... ^^^^ , potato diet > all.

Individuals that are capable of high postload insulin secretion may be the group most likely to accumulate fat on a high-glycemic-load diet and find weight loss difficult 

Now this is an interesting perspective, instead of the view that fat gain protects against diabetes, we can flip this around and say that rather than getting pancreatic failure and failing to produce insulin, people resistant to type 2 diabetes have infact a super pancreas that will hyper-secrete insulin to keep up hyperglycemic demands, the result of the hyper-insulin secretion ofcourse being obesity.

Kind of the same theory, but approaching from a different angle.

Any healthy diet that reduces postprandial glycemia and insulinemia, including high-protein, lower-carbohydrate diets, Mediterranean-style diets, and low-glycemic-load diets, may be preferable to the conventional high-carbohydrate, low-fat diet

Obviously you forgot to mention that the diet must also be low-reward. Thats right, isnt it?       ??????

Adipose GLUT4 Knockout

Well, not really knock-out, but a severe deficiency nonetheless, of GLUT4 only in the adipose tissue. I was after this paper to try and help me distinguish between the affects of insulin and glucose uptake into adipose tissue and how it might influence obesity.

From this model we learn that.....

  • In adipocytes, basal glucose uptake is reduced by 40%
  • In adipocytes, insulin-stimulated glucose uptake is reduced by 72%
  • Growth and body fatness are normal
  • Glucose transport into skeletal muscle is impaired by 40%, despite intact GLUT4's in muscle.
  • The ability of insulin to inhibit liver glucose production during hyperglycemia was 50% reduced.

So the surprising conclusion from this study is that reduced GLUT4's in adipocyte's gets you severe metabolic disturbances with insulin resistance in both skeletal muscle and liver. Contrast this to the FIRKO mouse however, that is metabolically healthy. This to me indicates that it is a reduction in this thing "basal" glucose uptake into adipocytes that is causing metabolic issues, and not a reduction in insulin-stimulated glucose uptake per se.

The basal glucose uptake is something important to note, I.E. , there is uptake of glucose into adipocytes even without insulin.

A possible link is "this" paper. In short, there is another serum protein, that is yet unidentified, that is also responsible for GLUT4 expression on adipocytes. This factor still functions in insulin resistance, and critically does not activate the same repertoire of downstream signaling molecules that are implicated in insulin-induced GLUT4 expression.

OK OK, so where does all this stuff leave us anyway?

We also have to recall that overexpression of GLUT4 on adipocytes results in increased fat mass accompanied by gross adipocyte hyperplasia. Is there anyway to "over-express" GLUT4's on adipocytes without being a transgenic mutant? Ofcourse there is, its called INSULIN dummy. With all the above in hand, I can only conclude that it is insulin-stimulated glucose disposal into adipocytes that is a method of creating obesity. "Basal" glucose uptake into adipocytes, perhaps via this unidentified serum protein, appears to be both healthy and actually necessary for proper metabolic health.

Wednesday, 19 December 2012

Quick note on MIRKO mouse

Here it is again, for the 1000th time, increased glucose disposal into adipose tissue = fat tissue growth = obesity.... ( bolded part for emphasis )

White adipose tissue (WAT) plays a critical role in the development of insulin resistance via secretion of free fatty acids (FFA) and adipocytokines. Muscle-specific insulin receptor knockout (MIRKO) mice do not develop insulin resistance or diabetes under physiological conditions despite a marked increase in adiposity and plasma FFA. On the contrary, WAT of MIRKO is sensitized to insulin action during a euglycemic clamp, and WAT glucose utilization is dramatically increased. To get insight into the potential antidiabetic role of MIRKO adiposity, we have studied insulin action in WAT during a euglycemic, hyperinsulinemic clamp, and we have characterized the morphology and biology of WAT. During the clamp, there is no alteration in the expression or activation in the insulin signaling molecules involved in glucose transport through the phosphoinositide 3-kinase/Akt and CAP/Cbl pathways in WAT from MIRKO. The 53% increase in WAT mass results from a 48% increase in adipocyte number (P < 0.05) without alteration in cell size and contemporary to a 300% increase in mRNA levels of the adipogenic transcription factor CCAAT enhancer binding protein-alpha (C/EBP-alpha) (P < 0.05). There is a 39.5% increase in serum adiponectin (P < 0.01) without modification in serum leptin, resistin, and TNF-alpha. In conclusion, the MIRKO mouse displays muscle insulin resistance, visceral obesity, and dyslipidemia but does not develop hyperinsulinemia or diabetes. There is an accelerated differentiation of small insulin sensitive adipocytes, an increased secretion of the insulin sensitizer adiponectin, and maintenance of leptin sensitivity. The MIRKO mouse confirms the importance of WAT plasticity in the maintenance of whole body insulin sensitivity and represents an interesting model to search for new secreted molecules that positively alter adipose tissue biology.

and this......

During a glucose tolerance test, MIRKO mice show an increased glucose utilization in WAT, which ultimately results in increased fat mass

 Dont listen to me though, insulin doesnt make you fat, just keep counting those calories and moving more.

Friday, 14 December 2012

Guyenet solves obesity & insulin resistance connection.

Guyenet posted a paper which with 1 picture tells me everything I have thought was true is most likely true. That fat tissue growth ( adipocyte hyperplasia ) protects you from insulin resistance.

The insulin-sensitive person has clearly been able to grow new fat tissue as evidenced by the many small adipocytes you see in the picture, meanwhile the insulin-resistant person has fewer and larger adipocytes, the in-ability of fat tissue to grow is causing insulin resistance.


Because large bloated adipocytes are themselves more insulin resistant, which means less glucose uptake and less production of the lipokine palmitoleate. This lipokine released by adipocytes  is what keeps whole-body insulin sensitivity good ( glucose uptake by adipocytes is also defined as "good" insulin-sensitivity ). Dont worry if your gaining weight in the mean-time, so long as you can stay insulin sensitive so that you can keep guzzeling down loads of that cheap glucose we're selling, gotta keep our consumerism society going you know.......

I suspect the person on the left, the insulin sensitive individual, with all his nice new small adipocytes, would have a SIGNIFICANTLY harder time trying to lose weight if he did ever diet.

Oh and I just spotted this little gem in the discussion of the same paper....

It has recently been demonstrated that adipocyte number is a major determinant for fat mass in adults ( link )

This is as I said on Guyenet's other post, but I was larger ignored or challenged.

To me its clear, fat cell number determines your "body-fat" setpoint. The more fat cells you have, the fatter youll be. period.

And as I also have posted on previously, this convinces me more than ever that the only true cure for obesity is adipocyte apoptosis.

Thursday, 13 December 2012

I need to cut Carbs......

Still doing 23/1 but ive stalled on the weight loss, although I have been eating a fair amount of carbs recently. Its not my fault, carb appetite goes up in the winter, exactly when you are most glucose intolerant. Other than that, it is generally just alot harder to lose weight in the winter, despite a higher metabolic rate in response to the cold, I think in general people gain weight in the winter.

Its simple, I need to cut the carbs to continue weight loss, I know it. As fantastic as 23/1 is, ( Im amazed I havent actually gained weight from the carbs ive been eating ), there comes a point where you just gotta get the insulin lower.

Through meticulous observation, I have come to see how my body reacts to certain foods. For myself, I have found that food generally falls into 4 distinct categories when it comes to weight control.....

1 ) Foods that actively promote weight loss - vinegar, coconut oil, whey protein, fish/omega3

2 ) Foods that "allow" weight loss to progress - meat, eggs, cheese, vegetables, cream, seafood, butter

3 ) Foods that slow weight loss and/or promote weight stability - Milk, Yogurt, nuts, fruit*** ( not banana )

4 ) Foods that actively promote weight gain - rice, potato, pasta, bread, banana, wheat, fruit juice, anything with added sucrose.

Im still puzzled by Dairy, despite it being highly insulinogenic, I havent been able to figure out why it doesnt cause weight gain in the same way that starch and sugars do. Dairy may produce a strong GLP-1 response, but I have a feeling that it is something to do with increased glucose disposal into adipose tissue that promotes the weight gain. Yogurt sweetened with sucrose is fattening, but plain yogurt is not.

Friday, 7 December 2012

Another look at why LIRKO cant get fat

I have to string together a bit of a loose argument here, I may be wrong, but I want to put this post up anyway.

CarbSane smugly made this post today, although in the original paper the researchers report that the LIRKO mouse has "intact" insulin signalling in adipose tissue, im slightly suspicious of this.....

The MIRKO ( muscle insulin receptor knockout mouse ) is infact obese, here it is easy for me to speculate whats happening, a lack of glucose disposal in muscle is resulting in excess glucose disposal into adipose tissue and thus causing it to grow. A study from 1993  looked at over-expressing GLUT4 in adipocytes, which resulted in increased glucose uptake into adipose tissue.

The outcome was an obese mouse but the surprising finding was the main form of fat mass increase was adipocyte hyperplasia , and not adipocyte hypertrophy.  Scary thoughts...... Adipocyte hyperplasia ( fat tissue growth ) is caused by fat mass increasing its glucose uptake.

In 2004 Khan's research group ( who is responsible for developing the insulin-receptor knockout line of mice ) did another experiment with the LIRKO mouse where they administered the dreaded PPARγ agonist rosiglitazone to the LIRKO. 

Now here's where I get speculative.....

In the abstract, Khan reports that rosiglitazone caused an increase in adipocyte size in LIRKO mice, but a decrease in adipocyte size in normal mice.  The primary way that rosiglitazone improves glucose tolerance is by stimulating the production of new, small insulin-sensitive adipocytes, i.e. fat tissue growth. This is why in the normal mice it produced a decrease in adipocyte size,  there were born more new adipocytes, and the fat mass re-distributed over the higher number of fat cells.

But not in the LIRKO, no, rosiglitazone  just made them gain adipocyte volume, the last line of the abstract is where its at....

 but both metformin and TZDs require an operating insulin signalling system in the liver for their effects in glucose homeostasis.

Remember what we just said above, TZD's improve glucose homeostasis by making fat cells multiply, if TZD's failed to improve glucose homeostasis in the LIRKO mouse then this implies that TZD's failed to cause fat cell multiplication in LIRKO. The conclusion I am drawing is as quoted, an "intact" insulin signalling system in the liver is required for fat cell multiplication and thus the development of obesity.

So the hyperinsulinemia in LIRKO probably fails to result in obesity because for some reason the PPARγ adipogenesis pathway in adipocytes is not working.

Hepatic insulin resistance is sufficient to produce dyslipidemia and susceptibility to atherosclerosis.

Hepatic insulin resistance is sufficient to produce dyslipidemia and susceptibility to atherosclerosis.

I havent seen this study before. So hepatic IR is indeed the cause of metabolic syndrome. But we already know what causes liver insulin resistance, it is elevated ChREBP in the liver, which essentially derives from a combination of high carbohydrate consumption, and also frequent carbohydrate consumption.


I just had this flash up aswell..

Hepatic insulin resistance directly promotes formation of cholesterol gallstones.

From reading the abstract its our old friend FoxO1 which causes this, as in metabolic syndrome, hyper-active FoxO1 promotes gallstone formation.

What is required for obesity?

This post is something of a reply to Guyenet's latest post, whereby he ends with the line "and it certainly does not erase all previous evidence suggesting that hyperinsulinemia isn't required for obesity"

This is true, and is actually obvious.

Obesity is the accumulation of excess numbers of adipocytes, and excess adipocytes can only occur in the presence of adipocyte multiplication also called adipogenesis or simply fat tissue growth.

So whats the controller of adipogenesis?

Well, so far the research has pinpointed the transcription factor PPARγ as the "Master regulator" of adipogenesis. Without PPARγ precursor cells are incapable of expressing any known aspect of the adipocyte phenotype.

Also check out this line from this abstract.....

PPARγ is the master regulator of adipogenesis, thereby stimulating the production of small insulin-sensitive adipocytes.

That part I bolded should be sending off some alarm bells in your head now with regards to PPARγ. Theres no question, if you want to get fat, just stimulate the PPARγ transcription factor inside your adipocytes....

So the next question is, what controls PPARγ in adipocytes??????????????????????

Insulin acutely regulates the expression of the peroxisome proliferator-activated receptor-gamma in human adipocytes

With this line.....

In explants of human adipose tissue, PPAR-gamma protein levels were significantly increased (42 +/- 3%, P < 0.05) after 12 h of incubation with insulin

That sounds something like hyperinsulinemia to me, and if hyperinsulinemia increases PPARγ, you can bet your ass that hyperinsulinemia can make you fat. The point though is that it is the downstream affects of insulin acting on the adipocyte to stimulate PPARγ that fundamentally produces obesity. Hyperinsulinemia in and of itself will be useless in producing obesity if its not hitting adipocytes and/or stimulating PPARγ.

Its very likely the FIRKO mouse cannot get fat because it cannot stimulate PPARγ inside its adipocytes.

Thursday, 6 December 2012

Insulin Therapy causes weight gain

Long-term, intermittent, insulin-induced hypoglycemia produces obesity without hyperphagia or insulin resistance: a model for weight gain with insulin therapy.

I was researching some of the older studies done by Levin BE, when I found this latest study today. Apparently, its a mystery to him why insulin causes weight gain.

Insulin treatment caused a significant increase in both body weight and fat mass, accompanied by reduced motor activity, lowered thermogenesis in response to a cold challenge

Its likely that exogenous insulin therapy could be mimicked by the body in vivo, whereby you secrete extra insulin in response to carbohydrates mainly because of hepatic insulin resistance. And as per insulin therapy,  weight gain will ensue. The researchers report that the weight gain occurred in the absence of increased food intake, I have to keep repeating stuff like this because the calories in calories out meme is tough to vaccinate.

Anyway, as I said I was looking at some of the earlier research by Levin from the 1990's and he has quite a big repertoire of studies looking at "high-fat" diets in rats. Infact Levin commonly switches between using the phrase "high-fat", "high-calorie", "calories-density", in each case the diet is the same, it is a mixture of sucrose and fat, and it is quite clear that it is the sucrose causing the problems but Levin seems hesitant to acknowledge this in the texts, never mentioning the phrase "sucrose-based" diet.

One of the things Levin noted early was that there was a genetic predisposition to becoming obese on this sucrose + fat diet, as he noted, only about 50% of the rats became obese on this diet, with the other half gaining the same weight as chow fed peers. ( This genetic variance reminds me of the phenomenon in humans  whereby some people eat endless sucrose and never get fat, while others get fat easily on sucrose )

Levin, like most of the obesity research community, has been mislead and side-tracked by the discovery of red herring, leptin, in 1994, but his earlier research focused on the ability of oral or intravenous glucose to stimulate norepinephrine release into the plasma, and critically, that this increase in norepinephrine predicted which rats had the genetic predispotion to become obese on the sucrose-fat diet.

The relationship was, more norepinephrine AUC = more weight gain.

I will make another post after ive looked at more of Levin's earlier research, but to sum it up, it has something to do with the nervous system, and the brain sensing of blood glucose levels and norepinephrine release into the plasma.

The fact that higher norepinephrine plasma is correlated with weight gain leads me to think that it is catecholamine resistance in fat cells causing the problem here. Although its easy to blame insulin for weight gain, there is actually 2 sides to this story, as catecholamine resistance in fat cells will also lead to weight gain BECAUSE a lack of catecholamine binding will increase insulin sensitivity in fat cells, without any extra insulin from the pancreas.

Monday, 12 November 2012

High-carbohydrate diets induce hepatic insulin resistance

Sometimes you get lucky and fall on something you wasnt actually looking for. I was doing some research on the possible relationship between FoxO1 and ChREBP in the liver ( more on that possible link in a moment ) when I found this little theory paper.

High-carbohydrate diets induce hepatic insulin resistance to protect the liver from substrate overload.

If anyone can link the full text id be interested ( its behind a paywall ), but anyway, the abstract tells you the gist of this guys thinking. Recall that ChREBP is a transcription factor activated by high concentrations of glucose in the liver.

One of the important jobs of ChREBP is go into the nucleus and start spitting out enzymes that convert carbs to fat. ( like fatty acid synthase ). However in the abstract we learn that ChREBP also codes for glucose 6-phosphatase, and this enzyme in turn, stimulates production of Glucokinase regulatory protein ( GKRC ).

In turn, GKRC inhibits liver Glucokinase.

Remember that the activity of glucokinase determines liver glucose uptake because it relives the concentration gradient of the GLUT2 receptors on the liver, allowing more glucose to flow into the liver from outside. Glucokinase is also a target for insulin and GLP-1, and the activation of glucokinase by GLP-1 is probably a primary way that GLP-1 helps diabetics.

Sorry I didnt mean for this to get so technical!

So , to condense this guys theory, he is saying that hepatic IR is caused by ChREBP inhibiting glucokinase.

But I think there may be slightly more to it than that, I also found this paper which says that FoxO1 inhibits ChREBP.

From the last post we saw that FoxO1 codes for enzymes for gluconeogensis, but, ChREBP codes for enzymes that convert carbs to fat. Its probably not a good idea to have both FoxO1 and ChREBP running at the same, because the glucose you make from FoxO1 will get converted to fat by ChREBP? Which just means your going around in circles.

FoxO1 is suppose to mediate the fasting state, where blood glucose concentration is constantly replenished and muscles become insulin resistant to conserve glucose for the brain during.

My theoretical speculation is this, if the level of ChREBP is the liver is elevated due to high carbohydrate consumption aswell as frequent consumption, does this inadvertently force FoxO1 to be higher? Is FoxO1 hyper-active BECAUSE ChREBP is elevated? And yes, ChREBP is elevated in the liver of obese people as pointed out by Lucas.

Inhibition of ChREBP in ob/ob mice improves insulin resistance while deficiency ChREBP actually prevents obesity in ob/ob mice. Is there a connection between leptin and ChREBP?


Leptin activates AMPK  and in turn AMPK inhibits the activity of ChREBP. It is well reported that Metformin activates AMPK, so its looks like Metformin may also inhibit ChREBP, this is probably where the ability of Metformin to improve insulin sensitivity stems from. In that last study above they also report that vinegar supplementation ( 30ml per day ) slightly improved weight loss, acetic acid converts to acetate which activates AMPK and thereby inhibits liver ChREBP. The relation appears to be dose-dependent, so more vinegar = more weight loss. Up to 90ml per day was deemed safe.

Anyway, im quite convinced that it is liver ChREBP that causes hepatic insulin resistance. And if metabolic syndrome is the manifestation of hepatic insulin resistance then this implies liver ChREBP is the cause of metabolic syndrome.

Urgh, it IS the bloody carbohydrates!  

I think im just about done here..............

Saturday, 10 November 2012

Is FoxO1 making you fat?

I got this link from a comment that George posted.

FoxO1 is a transcription factor ( you can see a video here of what it does ). Its job is to enter the nucleus in cells, read the DNA sequence it binds to, and start churning out the peptides that that particular DNA sequence codes for. And it just so happens that FoxO1 codes for the enzymes involved in gluconeogenesis.

These particular enzymes are rate-limiting unfortunately, I.E. they determine the rate at which the process happens. The more of these enzymes you have active, the higher your rate of hepatic glucoenogenesis. So, loosely speaking we have........

High FoxO1 activity -> lots of gluconeogenic enzymes floating around -> high rate of hepatic glucose production.

The problem is further compounded by the fact that FoxO1 seems to cause insulin resistance in muscle, it causes muscle to start up-taking fat and burning it and ignore glucose oxidation, this will result in decreased muscle glucose uptake aswell. Recall that muscle is the primary site for peripheral glucose disposal after a meal. All the glucose in your blood after you eat a potato has to go somewhere, and if it doesnt get disposed of in muscle because of a high FoxO1 activity making muscle insulin resistant, it probably ends up being disposed of in adipose tissue.

Disposing of alot of glucose in adipose tissue promotes fat tissue growth ( obesity ). Remember the high levels of leptin seen in fat people being atleast partly a consequence of glucose going down the lipogenesis pathway inside adipocytes? Where did all that glucose come from anyway?

Answer:    it got rejected from muscle because muscle is insulin resistant because of a high FoxO1 activity.

Suddenly it all seems so clear, the idea that fat tissue growth "protects" you from diabetes would appear to be a very real phenomenon. Actually, I wouldnt really say fat tissue growth is "protecting" you, but rather it is masking the problem. The fat tissue is sucking up all the glucose that isnt being disposed of in muscle.

FoxO1 is where we finished with the recent Lustig paper, In it, Lustig talks about selective hepatic IR, where insulin is suppose to suppress gluconeogenesis after eating a potato, insulin is suppose to stop FoxO1 from entering the nucleus and therefore stop it from doing its job of making gluconeogenic enzymes during a time when blood glucose is naturally elevated because we've just eaten some glucose. The problem seen in metabolic syndrome is that insulin fails to properly suppress FoxO1 in response to potato eating.

It is also likely that hyper-activity of FoxO1 is causing the elevated fasting blood sugar in MetSyn.

The question that Lustig couldnt answer, and the question that may well be the answer to the whole diabesity epidemic is, why is the FoxO1 transcription factor so hyper-active?

Tuesday, 30 October 2012

Tricks to reduce postprandial glycemia

Just a quick post to summarize some of the tricks one can use to reduce postprandial glycemia and thus postprandial insulin. I would advise people to have a quick look at the links aswell.

1 ) Eat your protein and fat first, eat your carbs last. Eating your fat and protein first will slow gastric emptying ( 1, 2 ) *the other effect is ofcourse eating protein + fat with your carbs will make the chyme that  passes from your stomach into your intestines less carbohydrate dense, reducing the concentration of glucose in the chyme and thereby delaying glucose absorption.

2) Vinegar is an effective way to reduce the glycemic impact of starch. Add 2 tablespoons ( 30ml ) of vinegar to your  potatoes/rice, ( or sip it before the meal ) ( 3 ) Im not sure of the mechanism that vinegar helps but I think it may be due to acetic acid being converted to the short chain fatty acid acetate which in turn stimulates GLP-1. The fact that vinegar supplementation increases satiety would support that theory.

3) MSG,  as recently posted,  the researchers found that 2g of MSG added to a carbohydrate + protein meal significantly reduced postprandial glycemia and insulin. The mechanism is a strong increase in GLP-1 stimulated by the MSG. Enjoy a few tablespoons of soy sauce before downing the carbs.

4) Fructose, the literature indicates that small dose fructose is actually beneficial to glycemic control, with the mechanism being that fructose helps activate glucokinase. ( 4 ) The activation of this enzyme is VERY important for your glycemic control. A study has shown that the consumption of small dose fructose  ( 10g ) some 30-60 mins before the carbohydrate meal reduced postprandial glycemia, while the consumption of that same fructose with the meal did not produce any significant change in glycemia. Original link from SuppVersity ( 5 )

So.... take 25g of honey 30-60 minutes before your carbohydrate meal, honey is rich in fructose and has been shown to reduce hyperglycemia in diabetic's ( 6 )

Hepatic glycolysis seems to be important in controlling body fatness, ( 7 ), this study reports that proper handling of the glycolytic enzymes helps control ( lower ) hepatic glucose production, reducing whole-body glucose disposal and therefore enhancing peripheral fatty acid oxidation since the glucose utilization in those tissue's is reduced. This ties in directly with the observed fact that people with higher 24h respiratory quotients are prone to weight gain, because higher 24h respiratory quotients indicates a higher rate of glucose oxidation compared to fat oxidation.

More research in this area is warranted.

5) Eat carbs only late afternoon / nighttime. Again as I posted on before, cortisol is very high in the hours following waking up. Hepatic glucose production will be high during this time, along with insulin resistance. BBC horizon reports that blood pressure is highest upon first waking up in the morning, blood vessels are stiffer during this time, and your blood is even more "sticky" during the morning.

They report that this time in the morning is statistically the highest time of the day for heart attacks to occur.

Let me assure you, chowing on cornflakes, orange juice and toast for breakfast is the most moronic thing you can do for your health. Nothing like spiking your blood sugar and insulin first thing in the morning when your hepatic glucose production is raging, your blood is sticky and your blood pressure is high!!!!

Diurnal Cortisol comes down in the late afternoon and evening, making you more insulin sensitive, so this is naturally the best time to eat carbs. A study has shown greater weight loss for equal calories when carbs are ingested mostly at night ( 8 )

Theres a funny fail in that BBC horizon show btw, later in the show there is some fool woman ranting about how breakfast is the most important meal of the day and is where you should get in most of your daily calories. Did she not watch the first half of the show detailing the increased blood pressure + sticky blood + cortisol? Jeeezzz.....

UPDATE(1) - Yamashita et al report that vinegar ( acetic acid ) is converted to acetate and this suppresses the transcription factor ChREBP in the liver. This is quite promising, as ChREBP is linked to fatty liver and insulin resistance.

Saturday, 20 October 2012

How much protein?

One thing I've quickly learned following the warrior diet is that eating enough protein is essential to surviving the 23 hour fast everyday. Those days I didnt pay attention to my protein intake and ate lots of vegetables/rice/potatoes ( which are quickly satiating in the short-term ), I experienced significantly more hunger and food obsession the following day, which starts early afternoon and continues right up until I eat at 6pm.

This heavy hunger and food obsession is absent on days where I had eaten alot of protein + fat the following evening for dinner.

Those studies claiming that boiled potato is the most "satiating" food per calorie are a fucking joke. Yeh sure, in the very immediate short-term plain boiled potato might be quite satiating, but try doing 23/1 IF while relying on that short-term signal from potatoes.

Aint happening dude.

Anyway, I just wanted to dust off this study where the researchers were looking for how protein inhibits AgRP. The graph that most caught my attention in the study was this one.......Rats fed either 10% or 20% protein diet...................

While I cant make any definite conclusions from this graph about exactly how much protein one should eat, what we can certainly say is that 10% protein is probably not enough, as 20% protein greatly suppresses AgRP. As noted by the researchers, low-protein diets increase food intake. ( The researchers also go on to show that it is leucine that has the big affect on suppressing AgRP )

Recall that AgRP is a starvation neuropeptide, it reduces energy expenditure by blocking MC4R signal transduction, it also increases hunger and even reduces fertility  ( as evidenced that ob/ob leptin deficient mice have fertility restored if you also knock-out AgRP. )

So if im eating 2500 calories per day, 20% protein means I need to get atleast 125g of protein per day. This fits in with my personal experience quite well, as I have observed I need about 125-150g of protein per day to feel "properly" satiated.

Would there be additional reductions in AgRP if we increased protein to 25% or 30%? Probably, but I suspect it would be subject to severe diminishing returns. From the evidence we have here, its probably best not to let your protein intake drop below 20%. I personally prefer around 25%.

Wednesday, 17 October 2012

Too many fat cells

This post from suppveristy clearly explains the problem better than I.

Adipocyte hyperplasia is THE problem why obesity is almost impossible to manage with dietary intervention.  The below picture shows the leptin secretion of a fat cell in relation to its volume, the relationship in non-linear, small type I fat cells secrete 200 leptin, while larger type II fat cells secrete 7 times as much leptin, 1400.

Because of the negative feedback loop inherent to all adipocytes that their insulin sensitivity varies with their volume, you will find that adipocytes in the same region of the body are approximately of equal volume. Spreading your bodyfat out over many adipocytes will severely compromise your leptin output. This is why dieted down people have reduced energy expenditure because for a given bodyweight they are leptin insufficient.

Why do weight loss stalls happen? Because you have reached a point where you have reduced adipocyte volume enough to be in balance with 24hour insulin secretion. To continue weight loss some adipocyte apoptosis is probably necessary.

Now we know why overfeeding studies fail to generate the obesity phenotype, because the overfeeding may not be enough to produce the sufficient adipocyte hyperplasia. If during overfeeding all you do is increase adipocyte volume, these stuffed fat cells will become increasingly insulin resistant and leak FFA, increasing energy expenditure ( or increasing ectopic fat accumulation ) until their volume decreases enough to become insulin sensitive again to be in balance with 24hour insulin secretion.

Whats the cause of the obesity epidemic? I think its as simple as this......

Foods high in glycemic index + glycemic load -> explosive insulin secretion -> adipocyte multiplication!

No need to talk about "calories"!

Spreadbury's Carbohydrate density graph is a correct illustration of the "causes" of the problem, but I think he has the wrong hypothesis, it is not leptin resistance, Rice cake diet anyone?

Monday, 15 October 2012

Starvation induced apoptosis

In the last post I made the claim that fasting and/or very low calorie diet was necessary for starting the apoptosis cascade. For some reason, low insulin does not in itself seem to be enough, otherwise we would expect ketogenic diet's to completely demolish bodyfat. But alot of people easily become weight stable on ketogenic diets, even at still elevated levels of adiposity ( I.E. famous weight loss stall ).

Perhaps part of the reason for this is that GLP-1 signalling in adipocytes also inhibits apoptosis. So even if you achieve very low insulin with ketogenic dieting, you will still inhibit apoptosis because with every meal you eat, you secrete GLP-1. I can't help but wonder if this is partly behind the reason why weight regain is so aggressive after cessation of low-carb dieting and trying to introduce carbs back onto the menu.

The low-carb dieting would likely favour reductions in adipocyte volume and perturb adipocyte apoptosis through continued GLP-1 secretion in response to meals.

There doesnt seem to be any easy way of getting rid of adipocyte over-growth sadly.

Something which has confused researchers for sometime is how shooting a bolus dose of leptin into the brain causes deletion of adipocytes by apoptosis. ( 1 )

Now that my understanding is more up to date, I expect the reason this is happening is because a sudden dose of leptin in the brain causes a sudden surge in sympathetic nervous system stimulation of lipolysis in adipocytes, leading to a surge in beta-oxidation and ROS production. This in turn, can induce apoptosis. ( 2 )

Saturday, 13 October 2012

Is Starvation the cure to obesity?

Im sure there are many people who would like you to believe this. Something to do with "negative energy balance" im sure they would say, displaying complete ignorance for the fact that biology employees countless homoeostatic feedback loops to keep certain parameters within a tight range.

Myself, I hate calorie restriction, it is nothing but misery and torture. Infact, I would rather straight up fast than subject myself to the inhuman suffering of eating less than what I feel like I want to.

When I eat, I want to continue eating until I get complete satisfaction, until my body naturally tells me ive had enough. I cant just eat a small meal for lunch, eating in this way just makes me MORE hungry. Im pretty sure now, I know why that is....... ( i.e. inhibition of hepatic fatty acid oxidation without the corresponding incretin secretion to offset the hunger ).

Do not under-estimate the contribution of hepatic fatty acid oxidation to whole body energy expenditure, even if organ mass makes up only 5–6% of body mass, it accounts for almost 80% of resting energy expenditure ( 1 ), Contrast this to muscle, which most people says keeps you lean, but according to Mark Sisson, a pound of muscle, at rest, burns about six calories per day. ( 2 )

Instead I expect the way that muscle helps keep you lean is because it helps improve nutrient partitioning towards there and away from adipose tissue by increasing insulin sensitivity and allowing more glucose/GLUT4 disposal in muscle, probably in the same sense that skeletal muscle LPL protects you from fat gain ( 3 )


I want to make a somewhat outrageous speculation that starvation "might" atleast in part be the cure to obesity.

First note, that obesity tends to involve more adipocyte multiplication/differentiation, rather than just an increase in adipocyte volume. ( 4 ) I.e. Fat tissue growth. This is what Thiazolidinediones do, and how they make you fat, new fat cells are born and because the are small, they are exquisitely insulin sensitive. I hope I dont need to convince anyone that adipocyte insulin sensitivity is a determinant of how big it can get......


Something we also know is that weight loss typically only involves reductions in adipocyte volume, not number, a drop in volume makes the adipocytes more insulin sensitive, and thus make you prone to weight gain. Despite all the complications in trying to find out why dieted down people regain weight so easily, I expect the answer to be as simple as this. i.e. a failure to reduce adipocyte number.

Consider the example...

Bob = 15% body fat,  500 adipocytes
Joe = 15% body fat, 1000 adipocytes

In this scenario, both joe and bob are just as fat as each other, by definition their adipose tissue is 15% of mass. Since bob has less adipocytes, it must follow that bob stores MORE TOTAL fat in each of his adipocytes. ( we have to also accept the pre-condition that in general, fat mass is dividend evenly between adipocytes, I.E. We dont store all our 15% fat in our belly and thighs. But the 15% is distributed over the entire body. )

Adipocytes that store more total fat are larger in circumference and so are less insulin sensitive.

Meanwhile joe will store less total fat mass in each of his adipocytes, meaning their circumference will be smaller and therefore meaning they will be more insulin sensitive. Joe will thus be more vulnerable to weight gain.

So a person who has lost weight, in the typical fashion of calorie restriction, can be just as thin as a lean person, but will probably have more total adipocytes, because as we just agreed, weight loss usually only involves reductions in adipocyte volume, not number. A tell tail sign of this is leptin. If your just as thin as someone else, but have less leptin, its most likely because you have more fat cells. Thats why  Thiazolidinediones are reported to either leave leptin unchanged or DECREASE leptin, because  Thiazolidinediones increase fat cell number.

Reversing obesity is all about reducing your adipocyte number, in addition to their size.

Short of surgical intervention to remove the excess fat cells, is there anything else that can be done? What about adipocyte apoptosis?

OK this is where my speculation gets outrageous, I wouldnt want to get anyone's hope up falsely! zomg!

A curious case of the man who fasted for 1 year ( 5 ), but what is most impressive, is that he only gained back 16 lbs after he stopped dieting. I dont know if he had any kind of surgery, or if he had just hulk like willpower, but I was intrigued after reading also this study ( 6 ).  It talks about a protein called CIDEA.

Apparently, CIDEA is involved in adipocyte apoptosis, and is negatively regulated by insulin. Starving fat cells and exposing them to very ( VERY ) low levels of insulin seems to induce, or rather, "allow" apoptosis. To quote....

After starvation for 72 h, numbers of adipocytes were decreased by 18.0 ± 7.7% and 6.6 ± 0.6% of adipocytes were TUNEL-positive

The adipocytes were incubated with or without insulin, and without insulin they started to self-destruct, this is because without insulin, adipocyte CIDEA starts to increase.

So my question is this, did the complete starvation in the 1-year man allow significant adipocyte apoptosis and thus inhibit his potential weight regain? Now, im not suggesting that you need to completely fast from food until you reach your goal weight.

Instead, what im thinking is that short bursts of fasting, perhaps 48-72 hours, could possibly enhance adipocyte apoptosis. And adipocyte apoptosis is absolutely necessary for "curing" obesity. Ofcourse at this moment in time, I dont have any in vivo evidence of this. Extrapolating from cell culture to in vivo has many flaws, not least of which is that nobody has zero insulin, even when fasting. But complete fasting is one of the few ways to get insulin to its lowest.

At this point, its worth remembering that Peter thinks that obesity can result from a failure to generate superoxide in adipose tissue, I.E. from a failure to make adipocytes insulin resistant. Mice that are deficient in NADPH oxidase 4 ( NOX4 ) in adipose tissue display increased susceptibility to obesity. What does NOX4 do? It is involved in the generation of superoxide. NOX4-derived ROS is a key modulator of adipocyte differentiation and mediates insulin receptor signaling in mature adipocytes in vitro.

Obesity in NOX4 deficient mice results from accelerated adipocyte differentiation and hypertrophy, and an increase in whole body energy efficiency.


So reduced superoxide in adipocytes leads to them multiplying and growing faster. But why am I talking about this? Is there a connection with CIDEA?

Besides the point that genetic Polymorphism in CIDEA is associated with obesity, Another team of researchers had a very interesting hypothesis, that CIDEA regulates fatty acid oxidation in adipocytes.  And we know that fatty acid oxidation in adipocytes produces superoxide, making adipocytes insulin resistant and protecting us from obesity. Further the researchers speculate that it is calorie restriction per se, that increases CIDEA.

The last link in the chain is if there is a connection between superoxide production and apoptosis. And I think the answer to this question could be yes, anti-HIV drugs are associated with lipodystrophy, and there are also associated with oxidative stress and ROS. This study reports that anti-HIV drugs increase oxidative stress and subsequently overwhelm antioxidant capacity and that this can lead to apoptosis.

Summary :-

For the TL:DR newbs, here is my theory..( its just a theory, I welcome criticism/feedback )

1) Fasting ( or SEVERE calorie restriction ) leads to increased CIDEA in adipocytes.
2) Increased lipolysis occurs along with increased fatty acid oxidation actually inside the adipocyte
3) Generation of oxidative stress and superoxide, leading to insulin resistance in adipocyte
4) Adipocyte insulin resistance along with low insulin from fasting leads to complete insulin insufficiency in adipocytes
5) Blindless to insulin removes protection of insulin mediated anti-apoptosis. ( i.e. insulin protects adipocytes from apoptosis )
6) Superoxide production overwhelms antioxidant capacity, eventually leading to apoptosis.

Monday, 8 October 2012

Overfeeding does not imitate obesity + Diet Update

One of the more common arguments we often see is that "over-eating" causes obesity by the mechanism of "positive energy balance", and part of the evidence for this is overfeeding studies, whereby we force feed animals or humans extra calories, and lo and behold, they gain fat mass and become "obese".

Or do they?

Do they really become obese?

Well, that really depends on how exactly you define "obesity". One of the most important characteristics of obesity, in addition to the obvious elevation in fat mass, is that this elevated fat mass is homoeostatically defended against by the body. Obesity is MORE than just a simple increase in fat mass. This is why overfeeding does not imitate obesity, because although we can successfully elevate the fat mass of organisms by overfeeding them, that elevated level of fat mass is NOT defended against. Instead, the organism easily returns to their original weight once the over-feeding ends.

This really is a critical distinction that is often overlooked in obesity discussions, and is exactly why obesity should be treated as a disease.

This paper is where I got this argument from, the paper also has many other interesting observations about the misconceptions of obesity, if you click on the PDF link its free access, the paper is not at all technical and is very accessible to the lay-person.

Diet Update

So ive been on the warrior diet ( 23/1 IF ) for 3 weeks now, and I think its going well. Lost about 6lbs so far, not amazing, I know I would of lost significantly more if I had been strict ketogenic but the advantage is that currently im not restricting any food groups and as such the diet is more sustainable. Im doing about 50/50 high-carb to low-carb days, the fact that ive lost weight while eating in excess of 2500 calories per day is especially motivating.

This is the longest ive ever been on 23/1 IF, in the past I tried to do it with strict low-carb but I always fell off the wagon because combining low-carb with 23/1 was too restrictive. Maybe its time for me to finally accept that I cant do low-carb for life, ive been on and off low-carb for the last 10 years because I cant sustain it longterm. Although I still gain weight easily from carbs, my weight is far more manageable doing intermittent fasting.

Im amazed at how the diet has changed my feelings towards food. I no longer get any sort of food cravings, the desire to eat during the day has waned greatly, the desire to eat for pleasure, to eat out of boredom etc those feelings towards food have completely vanished. Now I eat to satisfy hunger, and it feels great.

Sometimes I get very heavy hunger pangs around lunchtime, 2pm, but it quickly goes away within 30 minutes if you can resist it. Alternatively I can just take 25g of coconut oil and the hunger will go away. Coconut oil will not take you out of the fasting state because the short and medium chain fats directly enhance liver fat oxidation.

I eat my meal between 5pm-8pm everyday, I make sure its always high protein, something like 120g, eating low protein makes it very hard to do the 23hour fast. If I dont feel im going to get enough protein from the meal I supplement 60g of whey. Despite whey being highly insulinogenic, it seems to be very favourable for body composition ( 1, 2 ), in the past I had thought of whey as just a gimmick, but there is some science to back it up.

Something else that seems to be important is the order of eating, I feel much better if I eat the carbs AFTER the protein + fat. If I eat the carbs first it takes more food to satiate me and I feel more hungry the next day. My first impression is that the protein + fat first delays gastric emptying and potentially lowers the glycemic index of the carbs.

A big disadvantage to this style of eating is the large meals at night can completely sedate you, youll be lying on the couch / bed for 2 hours after eating waiting for the food digest and your big stomach to shrink.

Thursday, 4 October 2012

Viagra for shift-work?

Well well, wonders never cease, I read a curious article today about how Viagra can actually help circadian phase shift advancement ( recall that advancing the circadian rhythm is substantially harder than delaying it ) , and was lead to this study

I love self experimentation, so now I just gotta pluck up the balls to go into my local boots store and get some. I think Ill use it in the morning right when im advancing the circadian rhythm with the light box.

In other news, im contemplating getting a Vitamin D lamp.

Sunday, 30 September 2012

Monosodium glutamate stimulates secretion of GLP-1

I found this cute little study today, if you follow the link from pubmed and click on the PDF you can get the full text for free.

In the study they made people drink test meals containing alot of carbohydrate and protein, and added either 2g MSG or some salt to them. The group that drank the test meal spiked with MSG had reduced postprandial glycemia ( good ) and significantly increased GLP-1 secretion ( good )

How quaint!

Ive blogged thousands of times on the beneficial effects of GLP-1 with respect to body weight control, glucose tolerance etc so im not gonna bother rehash its merits here, suffice to say that I think all the controversy surrounding MSG is overblown and false. Ive never had a problem with it myself, and I absolutely love things like parmesan cheese, soy sauce, marmite etc etc.

So does this mean consuming MSG may actually be beneficial? MAYBE. Indulge in self-experimentation is what I would say.

suppversity also has a very comprehensive post on MSG.

Saturday, 29 September 2012

I must be mad to think this.... ChREBP

Liver-specific inhibition of ChREBP improves hepatic steatosis and insulin resistance in ob/ob mice.

  • ChREBP plays a key role in the control of lipogenesis through the transcriptional regulation of lipogenic genes, including acetyl-CoA carboxylase and fatty acid synthase
  • Liver-specific inhibition of ChREBP in ob/ob mice markedly improved hepatic steatosis by specifically decreasing lipogenic rates.

Obviously we need to be careful here because we are dealing with ob/ob mice, but the message is clear, ChREBP induces lipogenic gene expression. No doubt this is partly responsible for the fatty liver in ob/ob mice as demonstrated in the last bullet point above. The point I want to deduce however is that, if ChREBP favors "lipid accumlation" in the liver, what do you think ChREBP is doing in the adipose tissue? Surely it must favor lipid accumlation there aswell??!  I.E.    OBESITY.

I must be mad to think this right?

The only conundrum I have to contend with is the study in Lucas Tafur's post which showed that obese people have reduced levels of ChREBP in adipose tissue compared to lean people. Such confusion! But perhaps this phenomenon is observed because the obese people are already fat. It should stand to reason that for a given particular individual, their potential to get even fatter is steadily reduced as they fatten up. In this situation it makes sense that adipocyte ChREBP would decline as they become obese.

We also have the notion from the study I linked in my previous post, this one, they showed that per adipocyte, glucose uptake is less in obese people compared to lean people. BUT, and here is the punchline, this is over-compensated for by the fact that obese people have more total fat tissue. This fits in with the above idea that adipocyte ChREBP is reduced in obese compared to lean.

Something else just clicked this morning aswell..... remember how I posted that fat issue growth drives over-eating, and NOT the other way around? ( 1 ) Well check out this study again.....what does Troglitazone do? We established last post that it most likely encourages fat tissue growth, no wonder the people taking Troglitazone reported increased hunger. duh!

I want to bookmark some studies below that I will look into in the coming days. If I find something interesting ill make a post!

Hidden variant of ChREBP in fat links lipogenesis to insulin sensitivity.

A novel ChREBP isoform in adipose tissue regulates systemic glucose metabolism.

Expression of the insulin-responsive glucose transporter GLUT4 in adipocytes is dependent on liver X receptor alpha.

On the role of liver X receptors in lipid accumulation in adipocytes.

Friday, 28 September 2012

Adipocyte ChREBP

ChREBP is something that Lucas Tafur talked about here. His post is a good primer on the subject of ChREBP but beware its quite a technical post.

Anyway, to simply put it, ChREBP is how your body REACTS to dietary carbohydrate. The picture in Lucas's post is such a fantastic illustration of exactly what "life" is.

"life" is quite simply dead pieces of matter REACTING to their environment. The reaction is usually always predictable and the same, which is why I am a strong believer in determinisim and why I refute the idea of "free will". .Anyway, I stumbled on quite a few interesting things involving ChREBP and its quite likely that its one of the important technical things missing in Taubes's Carbohydrate Insulin Hypothesis.

Troglitazone is an anti-diabetic drug that is used to "treat" diabetes. Essentially what this drug does is instruct your adipose tissue to get very good at sucking up blood sugar and converting it to fat, thereby helping to control hyperglycemia  Troglitazone has the well known side affect of weight gain. But how exactly does Troglitazone enhance glucose disposal in adipose tissue? Well, either it enhances adipose tissue glucose uptake OR it promotes adipocyte differentiation ( or probably some combination of the two ). Initially I thought it was the first option, which lead me to search for studies which showed that Troglitazone increased leptin, since we already know leptin secretion is a product of carb to fat lipogenesis.

So if I could find a study that showed Troglitazone increased leptin that would be pretty good evidence that Troglitazone increased adipose tissue glucose uptake, but instead what I found was this. This study says that Troglitazone decreases leptin in patients with BMI less than 30 but leaves leptin unchanged in patients with BMI over 30. This leads me to the conclusion that Troglitazone works primarily by adipocyte differentiation, probably with some secondary affects of increased adipocyte glucose uptake.

However, one thing we can be sure of though is that Troglitazone increases adipocyte ChREBP. ( 1 ) And Troglitazone makes you fat. So.........anything else that increases adipocyte ChREBP likely also makes you fat........... what else increases adipocyte ChREBP? Yes baby thats right, glucose + insulin. Another point made by that paper is this.....

ChREBP expression in adipose tissue is not significantly affected by the diabetic state

Once again, this leads me to conclude that diabetes is a manifestation of the adipose tissue failing to expand to accommodate for increased glucose uptake, i.e. your adipose tissue does not want to act as a sink for excess blood sugar during hyperglycemia. On the other hand, if your adipose tissue is happy to expand and suck up excess blood sugar, youll get fat instead of getting diabetes.

BTW, maybe its just a coincidence that one of the downstream targets of ChREBP is fatty acid synthase, and that some cancer's are associated with over-expression of fatty acid synthase. Cancer is also associated with metabolic symdrome......... But yeh,.....anyway....... its probably all just a coincidence. Probably.

Now, for some funny reason, I cant seem to find this study in pubmed...

analyses of adipose tissue lysates revealed greater fatty acid synthase (FAS) and acyl-CoA carboxylase expression in the HC fed groups, suggesting increased de novo lipogenesis following HC consumption. Increased lipogenic protein expression was also associated with greater nuclear levels of carbohydrate-response element binding protein (ChREBP) in HC fed rats.

And here's a brand new study looking at ChREBP in fruit flies! ( 2 ) You dont need to read the study or even the abstract, because the title tells you everything you need to know.....
Mio/dChREBP coordinately increases fat mass by regulating lipid synthesis and feeding behavior in Drosophila.

Monday, 24 September 2012

Possible Mechanism for the Carbohydrate Insulin Hypothesis?

I have long observed that some sources of carbs tend to be more fattening than others, and that the degree to which the carb source spikes your blood sugar is also a very good indication for how fattening that carb source is. Given that there is such a thing as the "low-GI" diet lends credibility to this theory, atleast in part.

Glycemic Index broadly speaking is defined as how fast a particular carb source spikes your blood sugar. I think this is missing 1 key aspect however, although I dont have a glucose carbon tracer study on hand to prove this, but I suspect that in the case of high GI foods that the total amount of glucose entering circulation is also higher in addition to the speed at which it raises blood sugar. Foods that contain a high density of simple glucose molecules should likely be the worst for blood sugar control, and probably also obesity.

This quote is from the wikipedia page on glycemic index

Recent animal research provides compelling evidence that high-GI carbohydrate is associated with increased risk of obesity. In one study,[15] male rats were split into high- and low-GI groups over 18 weeks while mean body weight was maintained. Rats fed the high-GI diet were 71% fatter and had 8% less lean body mass than the low-GI group.

A higher amount of glucose entering circulation is a massive problem because hyperglycemia is toxic, it also puts immense pressure on the peripheral to act as a glucose sink in order to return to normoglycemia. The "peripheral" mainly consists of muscle and adipose tissue. I have already posted previously my theory that the high leptin seen in fat people is primarily a result of high-levels of the carb -> fat  pathway inside adipocytes. This is why carbohydrate density of foods is associated with high leptin, ( 1 ), because foods with a high density of simple glucose molecules simply results in more total glucose entering circulation.

More glucose entering circulation leads to more insulin leads to more glucose uptake by adipocytes leads to more lipogenesis pathway and finally leptin secretion.

As I posted on Wooo's blog here, my theory is that a high carbohydrate density and/or food that consists of mainly simple glucose molecules results in a high mass flow rate of glucose in the portal vein, this puts pressure on your liver to work "quickly" to handle all that glucose before it hits circulation. Through the activation of glucokinase, the liver uptakes the glucose through GLUT2 via simple concentration gradient. Due to physical limitations, there will obviously be a maximal rate at which glucokinase can phosphorylate glucose and thus maintain the concentration gradient.

But there is also the complication that some people secrete less glp-1 in response to carbohydrates, and since glp-1 also activates glucokinase, such people would have even more total glucose hit circulation when consuming high-GI foods. ( btw at present, no-one knows why some people secrete less glp-1 in response to carbs, the latest research says it has something to do with the high expression of UCP2 in the cells of the gut )

I am not alone in my theory that foods containing high concentrations of simple glucose molecules is inherently fattening, this research group is also onto it.... ( 2 ) They show that high-carb diets always leads to higher adiposity than isocaloric high fat diets. However the really interesting part was the change in adipose tissue gene expression, which included increased levels of GLUT4 on adipocytes. This fits in exactly with the idea that weight gain and adipose tissue expansion is an adaptive and protective measure initiated to protect you from diabetes. Actually, scratch that, it is an adaptive and protective measure to protect you from hyperglycemia.

Genes regulating glucose transport, glycolysis, fatty acid and triglyceride biosynthesis, desaturation and elongation, adipogenesis, and adipokines were affected by High-carb diets.

The adipose tissue literally changes its gene expression to accommodate for increased glucose uptake. Your adipose tissue "learns" to be very good at sucking up excess blood sugar. The same conclusion was reached by this group of researchers ( 3 ). To quote......

However, increased total fat mass provides a sink for the excess of glucose and compensates for insulin resistance.

I would like to speculate that reversing the obesity associated with excess carbohydrate consumption would involve undoing the change in gene expression in adipocytes, particularly that of increased GLUT4 utilization. Not eating a diet that aggressively spikes blood sugar could communicate to adipocytes that their increased GLUT4 expression is no longer needed. Another thing that comes to mind is anaerobic exercise,  its quite well known that anaerobic exercise improves body composition. I think that what may be happening is that the hypoglycemia challenges during such exercise send an additional signal to adipocytes that their increased GLUT4 expression is starting to actually become harmful. In response they may down-grade gene expression for GLUT4. ( ofcourse exercise also improves muscle glucose uptake so that is another mechanism by which glucose flux into adipocytes is reduced ).

Increased expression of GLUT4 on adipocytes promotes obesity ( 4 ).

So yes, I still believe in the carbohydrate insulin hypothesis.

Thursday, 20 September 2012

Circadian entrainment of metabolism

Warning!, sloppy and controversial post incoming!

My interest in the 23/1 intermittent fasting regime was piqued again recently after reading this link. Its about Ori Hofmekler's Warrior Diet, I read this book in the day, and although I did agree with it, the science has since come along more to support his ideas over the years. However I believe I can take his theory further and really get to the "liver" of the matter. I propose that Ori's theory is correct only in as so much as your circadian rhythm is aligned with the light/dark cycle.

If you maintain a circadian rhythm such that you sleep during the day and are awake at night, you should still be able to reap all the benefits of this 23/1, because the key point about the whole thing is really to fast during the hours following waking up, while your liver AMPK activity is high, and your liver is burning fat like crazy. Then, 9 hours or so after waking, when diurnal cortisol flatlines, liver AMPK activity starts to fall off, liver fatty acid oxidation slows, and this flips the switch that turns on hunger. You now have an approximately 4 hour window to get in your big daily meal. I say 4 hours instead of 8 hours because I dont advise eating a massive meal just before going to sleep.

Now I want to get more into the "liver" of the matter why Intermittent Fasting in general is oh so important .

First some important things to recall, hepatic fatty acid oxidation controls appetite. When hepatic fatty acid oxidation falls, hunger increases. I firmly believe that is NOT just a coincidence, but is actually part of the circadian rhythmic tone of food intake.

If you've been reading Peter's "Proton" series recently, you should know that fatty acid oxidation induces insulin resistance. High levels of fatty acid oxidation in the liver likely contribute to making it IR, especially upon first waking in the morning.

Next, the degree of PPARα activation in the liver is positively correlated with liver fatty acid oxidation. ( The paper in that post also suggests that PPARα activation may have the power to reverse fatty liver btw. )

I also went back to read the full text of this paper Lets ignore all the bullshit about high-fat-diet VS chow. I only want to look at the Ad Lib feeding vs IF aspect. The important graph from this paper imo, is this one....

Red line = IF mice, pink line = Ad Lib mice.

PPARα is a surrogate for liver fatty acid oxidation, we can safely say then that liver fat oxidation was substantially higher in the IF group. From the graph above we see that, after feeding in the IF group , PPARα shoots up then gradually declines until a few hours before feeding again. This essentially means that, all that time PPARα was elevated, hepatic fatty acid oxidation was increased and hunger was most likely diminished.

The decline in liver fatty acid oxidation before feeding is also important, because this would naturally make the liver more insulin sensitive. Exactly what we need before we cram food down our throats.

Fatty acid synthesis inhibits mitochondrial beta-oxidation. This right here, is the breaking of the CICO theory.

Malonyl-CoA, a product of ACC activity in the first step of fatty acid synthesis, allosterically inhibits mitochondrial carnitine palmitoyltransferase (CPT). CPT is essential for the transit of longchain fatty acids and acylcarnitine esters into the mitochondria for b-oxidation. Increased hepatic malonylcarnitine levels in FA mice, but not in FT mice (Figure S4B), are indicative of the specific disruption of fatty acid oxidation caused by impaired entry of fatty acids into the mitochondria.
And this.....

increased levels of the transcriptional repressor Rev-erba (Figure 2E) led to reduced expression of its direct target and a key lipogenic gene, fatty acid synthase


Food intake and insulin stimulate fatty acid synthase. ( 1 ) , this blocks liver fat oxidation which in turn stimulates appetite. In order to overcome that increase in appetite, you need incretins from the food you just ate. The satiating affect from the incretins you get must be enough to offset the hunger stimulated by the drop in liver fat oxidation. This is a good reason why eating big and rarely wins, while eating small but often FAILS.

So what controls the diurnal pattern of Liver AMPK and fatty acid oxidation in liver? I think theres a chance its ghrelin. ( 2 ) . As meal time approach's, the circadian clock of the gastric system starts secreting ghrelin more.  This has the affect of reducing liver fat oxidation, stimulating hunger, and allowing the liver to become more insulin sensitive in preparation for the feeding. ( 3 ) 

It should be apparent by now that circadian entrainment of food intake is as vital as circadian entrainment of sleep. If I told you I didnt sleep straight 8 hours every night, but instead slept in 3 small bursts of 3 hours, would you think that was healthy? How good do you feel when you get a solid 9 hours of deep sleep. Compared to continuously waking up in the night and lying awake for 1-2 hours before returning to sleep.

The discontinuous sleep makes you feel like shit doesnt it?

So why is it then, when it comes to food, which is also dependent on circadian rhythmic  

 tone, that we insist on getting our calories in 3 small short bursts? i.e. breakfast, lunch,dinner? If getting our sleep in one large burst is healthy and makes us feel good, why wouldn't getting our daily calories all in one burst also be healthy? I.e. 23/1 Intermittent fasting. 

( BTW yes I know the mice in the intermittent fasting study weren't doing 23/1, they were doing 16/8 , but as far as im concerned, the fact remains, eating at the SAME TIME everyday is as important as sleeping at the same time everyday. And dont randomly nibble on food, youll fuck up your circadian clock of ghrelin secretion leading to random hunger pangs, like randomly napping during the day can affect your sleep at night. Random nibbles also risks inhibition of liver fat oxidation while failing to generate necessary incretin secretion to keep you un-hungry, )