[Nikolas]

Obesity has presented itself as the modern world disease, with stunning calculations; nearly 30% of all non-violent deaths are caused or closely tied to obesity and associated health risks. Childhood obesity and the increasing presence of Type II Diabetes in children presents a major concern for the World Health Organization, with millions of dollars invested each year in obesity research and potential treatment.

Since the 1960 there has been a prevailing thought that obesity is not merely a consequence of life choices and diet, but that there is an overlaying genetic mechanism behind it. Only in the 1980 were scientists able to prove it, with the discovery of the leptin gene in mice, by dr. Jeffrey Freidman, who was studying obese and diabetic mice. He studied a genetic variant of the laboratory mouse which was inherently obese, and one that was diabetic. After several years of studies, research and experimentation, the scientists got a glimpse of a mechanism which was present in both strains, although in different ways. They discovered that the obese mice lacked the gene that produces leptin, a hormone secreted from the bodies fat cells, which is the body’s natural “stop eating” signal. These mice, literally did not know when to stop eating. The diabetic mice, on the other hand, had the gene and the hormone, but their brains showed less sensitivity to it, lacking the crucial receptor for leptin in parts of the brain.

The biology of leptin proved to be extremely complex and is still being worked on.

"If the fat mass falls," Friedman says, "the level of leptin falls, and the urge to eat goes up. After an eating binge, the level of leptin rises, which is a signal to eat less. In addition to modulating food intake and energy expenditure, leptin has an effect on fertility, temperature maintenance, and fat and glucose metabolism."

On the other hand, since this ground braking research, there has been a boom in obesity genetics research and studies, and there has been much progress; many new genetic components contributing to obesity and being overweight have been found and cross-linked to get a better understanding of the underlying mechanism.

Recently, a new study has been published by an international team of researchers, pinpointing a large number of genes linked to obesity, involving over 260 000 people worldwide. This new study shows that the genes contributing to obesity are in fact the same genes responsible for milder forms of being overweight; pointing out that the same basic mechanism is behind weight gain in any form.

"We know from experience that genetic factors are important for the emergence of both milder and more extreme forms of obesity, but how much overlap there is between genes that are involved in extreme obesity and normal or slightly elevated BMI [a measure of body fat] has not been examined systematically previously," study coordinator Erik Ingelsson, a professor at Uppsala University in Sweden, stated.
According to this study, obesity and overweight are the results of a greater number of genetic variants and interactions, rather than completely new genes being involved. Professor Ingelsson added that the results "suggest that extremely obese individuals have a greater number of gene variants that increase the risk of obesity, rather than completely different genes being involved. In the long term, our findings may lead to new ways of preventing and treating obesity, which is one of the greatest global public health problems of our age."

Other studies have pointed that obesity largely runs in the family, with twin studies showing up to 50% heritability. Many ongoing studies are concerned with childhood obesity, and have so far shown that it has in fact several components different from adult obesity, although they are severely linked. Childhood obesity, more than others, shows a strong genetic component, and is a good way to study the “obesity genes” as the children are less likely to be obese duo to environmental factors, such as diet and life-style.

Yet other studies have shown that obesity has a DNA regulatory effect, with the BMI (body-mass-index, the rough measurement of a body’s percentage of fat) and other obesity linked environmental factors have an impact on how genes are expressed.