Monday, May 19, 2014

Obesity: A Scale versus the Genes

There is a continual debate over the idea that:

Input-Output=Net Accumulation

This is always true, by definition.

However we should always examine what we mean by each term. Let us first examine Input.

Input= the net amount of kcal an individual obtains by the consumption of a certain type of food

Now that will depend on the food and the individual. Certain people have enzymes, products of genes, that convert the consumed more efficiently, and they also have epigenetic factors that enhance conversion of the consumed food into products that can be used or stored. Thus Input for one person consuming the same food as another is NOT the same. Genes play a part in how the physical raw input is processed in the individual to stored and used Input in the body. Thus the net Input, that which is used and/or stored, may vary in some statistical manner between humans.

For example certain southwest Indian tribes have genes that allow highly efficient absorption meaning that they can live on poor quality food but give rich foods they explode in weight and Type 2 Diabetes. Another example, epigenetic, is from Netherlands in WW II where in 1944 mothers were starved by Nazis and children born had epigenetic marks that allowed them to survive on low caloric intake by up-regulating certain genes. Thus genetic and epigenetic factors affect the conversion of Input and the net result can vary. The epigenetic factors can be passed down to children and in some cases to grandchildren. Thus environment via epigenetic changes can affect the genetic makeup.

Having said this, one can develop a distribution of net Input as a function of Gross Input, namely consumed food, and see that across a large population there is, one can assume, a Gaussian like distribution. Some people, most if you will, have a conversion rate of say 1, others may have a larger or smaller conversion rate. It does not appear that a great deal has been done examining this factor.

Output is basal metabolism rate and other factors whereby we burn calories. That also varies dramatically. You walk 5 miles and I walk 5 miles and we each urn a different amount. Again Output may vary from individual to individual. I may burn 100 kcal per mile walked and another may bur 75 or 125 kcal. Why the difference? Again it may be an amalgam of genetic or epigenetic. It may also be the way one walks. Therefore Output like Input has some form of distribution across large populations.

The problem thus is neither Input nor Output, it is Net Accumulation. Thus for zero Net Accumulation we each must understand our balance. Now that also may change as we may face different challenges.

Humans have the ability to use their intellect to measure a set point, namely a scale and to measure their weight. Secondly humans have the will power and intellectual capability to retain that set point.

Other animals spend all day hunting for feed and consuming generally low calorie food, and somehow maintain a balance. Rarely do we see a fat squirrel

The conclusions are:

1. Environment does affect what we see as net Input and net Output and thus net Accumulation

2. Genetics and Epigenetics affect what each individual does in terms of conversions

3. However as humans we have the ability/intelligence to measure the set point and the will to maintain it.

4. One size fits all does not work. Each human is different in how they convert Gross Input to Net Input and Gross Output to Net Output. Thus the only true measure is the scale, namely weighing oneself and balancing Input and Output to keep the scale at the required set point.

Thus when writes in the NY Times and other journals of note speak of diet and weight control we hear them state[1]:

FOR most of the last century, our understanding of the cause of obesity has been based on immutable physical law. Specifically, it’s the first law of thermodynamics, which dictates that energy can neither be created nor destroyed. When it comes to body weight, this means that calorie intake minus calorie expenditure equals calories stored. Surrounded by tempting foods, we overeat, consuming more calories than we can burn off, and the excess is deposited as fat. The simple solution is to exert willpower and eat less. The problem is that this advice doesn’t work, at least not for most people over the long term. In other words, your New Year’s resolution to lose weight probably won’t last through the spring, let alone affect how you look in a swimsuit in July.

All too often they oversimplify all factors. The basic law holds, it is a definition, a tautology. The problem is the conversion rates from Gross to Net, a factor that the authors above seem to struggle with but in apparent ignorance. Basically they argue about some set point theory. Namely humans eat until the set point and then stop. Eat too much, get fat, the set point increases and the system is unstable. Fat Squirrels! However this totally ignores the scale. If the goal is a BMI of 24.0-25.0 worst case, then just use the scale, reduce food intake by the use of the will until the scale falls back to the right range, and forget these putative set points, namely blaming some other factor. Take responsibility.

The authors continue:

If this hypothesis turns out to be correct, it will have immediate implications for public health. It would mean that the decades-long focus on calorie restriction was destined to fail for most people. Information about calorie content would remain relevant, not as a strategy for weight loss, but rather to help people avoid eating too much highly processed food loaded with rapidly digesting carbohydrates. But obesity treatment would more appropriately focus on diet quality rather than calorie quantity.

Obesity treatment is a non-issue by using a scale. Yes indeed, forget the calories, measure the pounds. Scales are cheap!