A problem with dieting rules is that only a small violation—a sneaky slice of cake, for example—is enough to derail the whole diet. Researchers call this the “what-the-hell effect”. 

Diets that require the dieter to follow rigid rules or forbid them from consuming foods they enjoy appear to be problematic, as they paradoxically increase the risk of overeating. 

When we are hungry, the hormone ghrelin stimulates the brain. Our brains pay more attention to cues for unhealthy foods—those which are high in sugar and fat—than healthy foods when we are hungry. 

It may be possible to train ourselves to ignore tempting cues.