As any dieter knows, when the going gets tough, chips and chocolate are all the more appealing. But it may not be simply a case of absence making the heart grow fonder.
Experiments suggest rapid weight loss alters the way the brain handles stress.
This means that when dieters are put under stress, even after they finish dieting, they are attracted to fatty foods. So dieting could actually end up making you fatter.
The American researchers looked at the effect of dieting on the brains and appetite of mice.
The animals’ food supply was cut by a quarter and they lost up to 15 per cent of their weight.
There were also important alterations to genes key to stress, while appetite and levels of stress hormones rose, the Journal of Neuroscience reports.
The researchers, from the University of Pennsylvania, then allowed the mice to eat normally and they regained the weight.
Initially, the ex-dieters ate similar amounts to mice that had never been put on a diet.
But when the researchers stressed the mice, for example by making noise, the ex-dieters gorged on fatty food.
Researcher Dr Tracy Bale said: ‘These results suggest that dieting not only increases stress, making successful dieting more difficult, but may “reprogrammed” how the brain responds to future stress.’