Friday, May 16, 2014

Obesity and Willpower

Does the law of mass balance really apply to human obesity? Namely does Input Less Output Equal Net Accumulation really work?

In a recent NEJM article one is asked to wonder. Everywhere else in the universe it applies but not for some strange reason in human obesity. The author states:

These studies, of course, reinforce what some physician–researchers have been insisting for more than a century: that obesity is innate, that weight regulation is not governed by a uniform tally of “calories in–calories out,” and to quote ..., that “there is a biochemical or basic biological element in what it is that we call `willpower.'” The views of many Americans notwithstanding, weight is clearly far from being entirely within an individual's control. Genetic predispositions, in tandem with the development of food environments that facilitate overeating and built environments requiring minimal energy expenditure, may help explain why so many Americans are obese today.

Unfortunately the statement is false, almost in toto. Yes, each person has a different set point, namely the Output level. Some people burn 1500 kcal per day and others 2200 kcal per day. There is no meter telling us that. In addition that Output number does depend on a lot of factors, stress, ages, health. But if Input exceeds Output then Net Accumulation occurs. The opposite is also true. Weight management is often a sophisticated balance, but the true meter is a scale. If one targets say a BMI of 24.0 then one just manages Input to ensure the 24.0 number is reached and maintained.

It is always nice to have that extra piece of pie, those cookies, that extra beer, I guess, but that is input. Yes there are people who eat anything and never gain a pound and those of us who measure calories each time we come near food.

As the author starts out:

The obese lack willpower; they overeat and underexercise — or so believe a majority of Americans. A 2012 online poll of 1143 adults conducted by Reuters and the market research firm Ipsos found that 61% of U.S. adults believed that “personal choices about eating and exercise” were responsible for the obesity epidemic. A majority of Americans, it seems, remain unaware of or unconvinced by scientific research suggesting that “personal choices” may not account for all cases of obesity.

No one doubts that there are a small few for whom weight control is highly problematic. No matter how low they go their Output is set well below that point. The few calories expended in exercise will never increase the output above the minimal input. But that does not account for the near global explosion of obesity. There was not a genetic change in humanity over the past thirty years to account for this. There is no epigenetic hyper/hypo methylation setting and resetting genes, causing massive reductions in basal Output. Input has increased by "choice" and all attempts to rationalize it as some effect out beyond human control is both wrong and harmful.

The law of mass balance applies. No one has ever rejected this. If it works in any chemical plant, and the human body is one, then it works in us. Remember the best meter is that scale and the best control mechanism is to not eat that extra candy bar or drink that extra soft drink. It is truly a shame that some physicians cannot call it for what it is. Oh, it appears as if the author is from the History Department at Harvard...