The Connection Between Leptin And Obesity

In many of the world’s industrialized countries today obesity has become an extremely common condition. Indeed, in the United States, which has the highest rate of obesity of any country, approximately 60 million adults are now considered to be obese and a incredible 9 million adults are classed as being or morbidly obese.

At first sight it may appear that this is nothing more than the result of changes to our diet and a significant drop in the physical activity levels for many Americans. However, scientific studies into the causes of obesity show that it arises out of a complex combination of factors. One such factor, which has been the subject of considerable study and debate over the past ten years is genetics and, in particular, the genes which are involved in the regulation of leptin within the human body.

Leptin (from the Greek word leptos meaning thin) is a protein hormone produced by fat cells and was discovered in 1994. Leptin is associated with the Ob(lep) gene which is found on chromosome 7 in human beings.

In very simple terms leptin enters the blood stream and travels to the brain, where a high level of leptin signals to the brain that the body has sufficient energy reserves or that energy reserves are too high and that fat needs to be burned off. As a result, leptin plays an important role in the regulation of both appetite and metabolism.

Levels of leptin found in the blood of obese people are usually very high and more than enough to suppress the appetite and to raise the metabolism. This does not happen however and it is thought that obesity might result from a resistance to leptin, in much the same way as individuals who suffer from type 2 diabetes are resistant to insulin.

The problem however is that the body is extremely complex and, alongside the Ob(lep) gene, there are clearly other genes involved in regulating appetite and metabolism. Additionally, leptin does not work alone and the way in which it triggers the brain and the chain reaction which it sets into motion is not fully understood at the moment.

It is difficult to say whether leptin really plays a part in obesity and the scientific literature on the subject does not support an association between the genes which regulate leptin and obesity.