One in three adults in the USA is considered to be obese: they have a Body Mass Index of 30 or more.
Obesity can have a disastrous impact on your health. Excess fat is most dangerous when stored in your upper body. You are more likely to suffer from diabetes, hypertension and heart disease.
A quick indicator if your weight is likely to be a health problem comes from your belt size: For men, a belt size of 40" (104cm) or greater indicates too much upper body fat; for women, a belt size of 35" (91cm) or greater indicates too much upper body fat.
It now appears that perhaps 50% of obesity is due to genetics rather than simply a weakness for food. There is a gene which produces a hormone called leptin. Leptin is part of a system that controls weight in the way that a thermostat maintains temperature. The sensor receives a signal, and thn makes adjustments so that an optimum level is maintained.
Evidence shows that leptin acts in a somewhat similar way. Weight is then maintained at a more or less constant level, leptin being the sense signal.
If we lose weight, the leptin level falls and that signal received, leads to our eating more. If we put on weight, by over-eating, our leptin levels rise signalling to the body to eat less.
There is a system that maintains a constant weight in all of us. It is thought that in many obese people the leptin doesn't work well enough that these individuals are not responding to the leptin levels, less signal gets through, so their body gets fatter.
In a smaller number of people, it has been found that their body doesn't produce enough leptin, at normal body weight and so they expand their mass accordingly.
While obesity is a complex issue and it is highly unlikely that it is as simple as being the result of a single gene, the understanding of leptin and its behaviour will help give some understanding of one of society's largest problems.
