KEY POINTS:
Women find it more difficult to follow a diet than men because they are biologically programmed to have less self control when it comes to appetite, a study into how the brain copes with food craving suggests.
An innate difference between the way men and women are able to deny themselves the pleasure of food could explain why women find it more difficult than men to lose weight and are more likely to be obese.
Scientists believe that men are able to voluntarily inhibit their internal cravings for food more effectively than women, probably because evolution has honed the female body - and mind - to absorb as many calories as possible in readiness for pregnancy and lactation.
"It's a very interesting observation but we don't really know why men are better than women at inhibiting their appetite," said Gene-Jack Wang, of Brookhaven National Laboratory in Upton, New York, who led the study.
"We have seen in clinical studies that men following a diet are able to lose about 10 per cent of their weight on average over a three-month period, whereas women manage a decrease of only about 5 per cent. We need to understand which areas of the brain are involved in this difference between the sexes."
The study, in the journal Proceedings Of The National Academy of Sciences, focused on the mechanism in the brain that controls appetite by suppressing food cravings.
The researchers subjected 23 non-obese volunteers to a 17-hour period of fasting followed by the sight and smell of their favourite food, which they were only able to savour without eating. Each of the 13 women and 10 men were asked to suppress their cravings through "cognitive inhibition" - self control - while the activity of their brains was being monitored by a positron-emission tomography (PET) scanner, which monitors how the brain uses glucose.
While the starved volunteers were subjected to the sight and smells of their favourite foods, parts of the brain involved in emotional regulation, conditioning and motivation "lit up", indicating they were stimulated by the food.
But when each person was asked to suppress these thoughts and use self control to inhibit cravings, only the men's brain scans showed a significant reduction in activity in the presence of food.
Such differences may explain why women have a greater tendency than men to overeat when tempted or under emotional distress.
Oestrogen is known to affect appetite, food intake and fat distribution but the scientists did not consider women's changing hormone levels - the next stage of research will include that data.
- INDEPENDENT
