If you've slaved for low-cal meals which, until now, has given you no visible results, scientists at University of Bristol have found why.
They have found that when people choose lower-calorie dishes, they just compensate by eating bigger portions.
During the study, researchers found that when faced with foods they liked, participants did not pick bigger portions of them than of any other food.
"A person's perception of how full a meal will make them feel will no doubt affect portion size. It's so important to be aware of behavioural triggers for over-eating," the Independent quoted Lisa Miles, a nutritionist at the British Nutrition Foundation, as saying.
The researchers, who studied the responses of 76 people to 18 different foods, found that people quickly learnt if food offered fewer calories per serving and upped their portion size to compensate.
"We know from experimental studies that eating large portions does not necessarily mean that you eat less at a subsequent meal, so this can lead to an increase in calorie intake overall," Miles said.
Dr Brunstrom, senior lecturer at the University of Bristol who led the study, will present these findings at a British Nutrition Foundation conference.