Saturday, 12 April 2014

Correlations in obesity

When dealing with obesity, its clear that people, including researchers and doctors, see what they want to see. IF they want to imagine obese people are simply lazy stupid gluttonous pigs, they will seek evidence to support that.

Stephan Guyenet has an interesting post up about the correlation between calorie intake and BMI. In his post we see a strong trend that as calorie intake increases, so does BMI.

But, is this cause or effect?

SURELY eating more food CAUSES increased BMI?

I got this study from a recent Mangan tweet

Here we see that total energy expenditure is higher in obese people, ( lean=2035, obese=2483, reducedObese=2033)

Further, as we look down the other graphs, we see that 24hr carbohydrate oxidation is higher in obese and reduced obese ( lean=218grams,    obese=308grams,      reduced obese=264grams ). Importantly, there are no differences in fat oxidation between lean and obese, BUT reducedObese have 28% reduced fat oxidation compared to lean aswell as 21% higher carbohydrate oxidation.

uh oh! Remember the link between higher RQ predicting weight gain? And we know that reduced obese people are highly susceptible to regain. And here we see evidence of reduced obese people seemingly relying more on carbohydrate oxidation.

However, things get really interesting when we consider these little snippets I dug up....

In particular, the bottom tweet. White Adipose Tissue oxidizes predominately glucose.

So now lets link everything together and see what correlations we have...

  • Calorie intake increases with BMI
  • Energy expenditure increases with BMI
  • Carbohydrate oxidation increases with BMI
  • Adipose tissue increases with BMI
  • Adipose tissue oxidizes mainly carbohydrate.
  • ?????????????

Yes, heres what im saying....

Rather than the same old bollocks of  "fat people are fat because they eat too much", instead we could speculate that fat people eat more calories BECAUSE they have more adipose tissue. And they are simply eating more to fulfill their bodies increased energy expenditure requirements.  The increased energy expenditure requirements appear to be ( atleast partly ) coming from them having increased carbohydrate oxidation needs, that is (probably) occurring BECAUSE of their increased adipose tissue mass.

So essentially we've come full circle, and we're back to the idea that, adipose tissue growth IS the cause of obesity and that probably Taubes was right, fat people eat more because they are getting fat.   because they are growing new adipose tissue.

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