Why dieting may not help you to lose weight

Looking to shed those extra kilos through dieting? You may be at a loss, as human bodies tend to compensate by sparing energy, limiting the number of calories that we burn and hence affect our weight loss regimen, researchers say.

According to the study, a group of neurons -- 'agouti-related neuropeptide' (AGRP) -- in a brain region hypothalamus contributes to the caloric thermostat that regulates our weight, regulating how many calories we burn.

When activated, these neurons make us hungry and drive us to eat, but when there is no food available, they tend to compensate for the reduction in calories.

"Our findings suggest that AGRP in the brain coordinate appetite and energy expenditure, and can turn a switch on and off to burn or spare calories depending on what's available in the environment," said Clemence Blouet from the University of Cambridge in Britain.

"When we eat less, our body compensates and burns fewer calories, which makes losing weight harder," Blouet added.

However, as soon as food becomes available and we start eating, the action of the AGRP neurons is interrupted and our energy expenditure goes back up again to normal levels.

In the study, published in the journal eLife, the researchers identified a new mechanism through which the body adapts to low caloric intake and limits weight loss in mice.

Using a genetic trick to switch the AGRP neurons 'on' and 'off,' they rapidly and reversibly manipulated the neurons' activity in mice, a finding that could help in the design of new or improved therapies in future to help reduce overeating and obesity, the researchers said.