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%.