Obesity has become an all too common condition in many of the world's industrialized societies today and is continuing to rise at an alarming rate. In the United States, which currently has the highest rate of obesity of any country in the world, some 60 million adults are classed as being obese and a staggering 9 million adults are considered to be severely or morbidly obese.

Although at first sight it might seem that this is simply the result of changes to our diet and a dramatic drop in the level of physical activity for many Americans in recent years, the reality is that scientific studies into the causes of obesity show that the condition results from a complex combination of factors. One such factor which has come under increasing examination over the past ten years or so is genetics and, in particular, the genes involved in the regulation of leptin within the body.

Leptin, which takes its name from the Greek word leptos meaning thin, was discovered in 1994 and is associated with the Ob(lep) gene [Ob - obesity, lep - leptin] which is located on chromosome 7 in human beings. In somewhat simplified terms leptin is a protein hormone produced by fat cells which enters the blood stream and travels to the brain, where a high level of leptin in the blood tells the brain that you have sufficient energy reserves or that your energy reserves are too high and that the body needs to burn off some fat. In essence therefore leptin plays an important role in regulating both appetite and metabolism.

In obese people levels of leptin found in the blood are normally very high and more than sufficient to suppress the appetite and increase the metabolism. This however does not happen and it is believed that obesity may be the result of a resistance to leptin, in much the same way that people suffering from type 2 diabetes are resistant to insulin.

The problem of course is that the human body is extremely complex and, along with the Ob(lep) gene, there are clearly other genes which play a role in regulating both appetite and metabolism. In addition, leptin does not work in isolation and the manner in which it triggers the brain and the chain of events which it sets into motion is not very well understood at this time.

As things stand today, it is very difficult to say whether or not leptin is truly a factor when it comes to obesity and the scientific literature on the subject does not support any real association between the gene, or genes, which regulate leptin and obesity. Nevertheless, with obesity growing at epidemic rates and our obsession with weight loss fueling an enormous weigh loss industry, the drug companies are now working alongside the scientific community and exploring this whole area in the hope of coming up with a suitable weight loss drug.