ALL the willpower in the world might not be enough to help you stick to that diet, say scientists who claim to have found the part of the brain which controls hunger.
New research led by scientists from Edinburgh University and Harvard Medical School suggests that a part of the brain may be “hard-wired” to seek food, as hunger-sensitive brain cells make it impossible for some people to resist snacking.
However, the researchers have found the specific neurons can be switched on and off, creating a feeling of fullness which could help in the development of drugs to tackle obesity.
The cells – known as AgRP neurons – detect when the body needs more calories and can drive overeating, the paper published yesterday in the journal Nature Neuroscience reveals.
Dr Alastair Garfield, a lecturer at the Centre for Integrative Physiology at Edinburgh University, said that these neurons acted as a kind of “handbrake” on food consumption of mice it was tested on, preventing the animals from overeating by making them feel full.
Dr Garfield said: “It’s not to say that people don’t eat for pleasure but what we see is the motivation to make the unpleasant feelings of hunger go away.
“If a pharmaceutical company could find a ‘magic bullet’ to deactivate the neurons then it could be useful in weight loss therapy.”
When the neurons are turned on – either artificially or by fasting – the mice would eat voraciously as they sensed low energy reserves.
But when they were off it would have a similar outcome to dieting, but without the gnawing feelings of hunger.
Dr Garfield added: “What is really significant is these cells are conserved in mice and men, meaning they are very similar.
“It makes the research much more meaningful.”
Professor Bradford Lowell, the study’s co-senior author from Harvard Medical School, said: “Turning on the satiety neurons had the same effect as dieting, but because it directly reduced hunger drive it did not cause the gnawing feelings of discomfort that often come with dieting.
“Our findings suggest that the therapeutic targeting of these cells may reduce both food consumption and the aversive sensations of hunger – and therefore may be an effective treatment for obesity.”
Professor Lowell said there is a theory that people eat to get rid of the unpleasant feeling of hunger, rather than because they love the taste of food.
To test this, the team built a two-chamber apparatus separated by a doorway through which the hungry mice were free to move back and forth.
If the animal moved into one chamber, computer software triggered the delivery of the blue laser light, which stimulated the neurons, whereas if they returned to the other chamber the laser was switched off.
The majority of the mice preferred the blue light chamber, showing how they were not experiencing negative feelings of hunger.
If the mice had already eaten a huge meal then they did not show a preference.