People should not be blamed for obesity, for some people's genetic make-up drives them to gain weight readily in an environment where food is freely available.

Dr Jeffrey Friedman of Rockefeller University discovered the obesity hormone leptin - which is involved in the satiety response - in 1995. He now shares his current thoughts on what makes people fat. There are two main factors contributing to obesity, he says - genes and environment.

Genetics accounts for the variation in weight in a population sharing roughly the same environment at a given time. And environmental changes drive the changes in obesity that occur in the whole population over time. Thus, some people always put on weight more readily than others. But the US population has been getting generally heavier because we have been eating more and exercising less. Some people are more sensitive - because of their genes - to these environmental changes and put on more weight.

In fact, Friedman adds, the genes of people who are obese now were probably advantageous to them in the past when food was scarce. While those who are lean today did not do so well in less abundant times. Environment changes far faster than our genetic make-up. What is needed now is a broad-based research program on how genes interact with environment, so that people who are obese - or at risk of becoming so - can be offered solutions based on sound science.

Source

Science 7th February 2003