by Always Wonder

Created on: February 01, 2009   Last Updated: February 08, 2009

Over the last decades, many theories have been developed and thrown over when it comes to explaining obesity. Thereby, a variety of angles have been used to tackle the problem - from an over - supply of energy, an under - supply of excercise, different macro - nutrients or foods to blame, to an inflammation caused by bacteria. The problem of most of these theories is not only that of little statistical support. Often, these explanations are impossible to test so they don't qualify for a scientific explanation in the first place.

Surely, one needs to differentiate between the usual overweight that occurs over a lifetime, the change in body composition that accompanies aging, and the concept of "obesity". Obesity is (at the moment) mainly defined by the statistical fact of being much heavier than one should be - given the average in a society.

This rather soft definition accounts for the fact that we still don't really know what obesity causes. However - the most likely cause for it is, I believe, rooted in genetics because up to today most of the major dis-functions of a human body have been found to be caused by differences in the way the genetic code is written or activated.

Moreover and unfortunately, the social mobility amongst the classes in a society is still extremely low - meaning that the correlation between being poor and being obese is also well explained by genetic heredity: A poor individual is more likely to be obese, and more likely to build a family together with a partner from the same background. The "genetic pools" between poor and rich groups in a society are less shared than within the social classes - obesity therefore stays, statistically, in the genetic pool of the poor rather than the rich and therefore causes a higher rate of obesity amongst them.

Not only that but also the history of the different societies (for example the American versus the Japanese) shows that the problems (such as famines and epidemics) that have been encountered and that have filtered the individuals that survived caused variations in the genetic and epigenetic make up between these groups. This might well explain the differences in the appearance of obesity amongst different societies. Another example for the difference in genetic make up and the impact this has on the human metabolism is the marked difference in lactose tolerance, or the ability to digest alcohol.

The sum of the evidence and the overall absence of any alternative explanation so robust let me vote in favour for "blaming" genetics for the obesity epidemic.

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