‘s Brookhaven National Laboratory in New York have shown that obese people have fewer brain receptors for dopamine and may eat more to stimulate the pleasure circuits in the brain.

The findings could offer a completely new approach to treating obesity, which affects up to a third of Americans and a growing number of people around the world. Weight reduction programmes, appetite suppressants and fat-blocker drugs have been used to combat obesity, but the Brookhaven scientists think targeting dopamine could be another line of attack. The researchers tested their theory on 10 extremely obese people and 10 others with a normal weight. Using sophisticated brain imaging, the researchers injected into each volunteer a chemical tag that binds to a dopamine receptor and then measured the signal from the tags. Strong signals indicated a high number of receptors. In the obese group they also noted an inverse correlation between body mass index (BMI) and dopamine receptors that wasn‘t evident in people with normal weight. BMI is a measure of weight relative to height. It is calculated by dividing a person‘s weight in kilograms by the square of their height in metres. A BMI of 18-25 is normal, 25-30 is overweight and more than 30 is obese. The obese people with the highest BMI had the fewest receptors. Wang and his colleagues said methods to regulate dopamine, either through drugs, exercise or behaviour modification could help obese people control their urge to overeat. REUTERS