If we're starting a diet, the first thing we think about heading for is the low calorie, low fat food options in the supermarket.
But, according to new research doing this is, in fact, could lead us to actually put on more weight.
Researchers at America's Purdue University have found that a person's body prepares itself to receive a large number of calories even when it tastes a diet version of a food. So when it only gets a low calorie hit, it confuses the body and actually makes you eat more.
Susan Swithers, professor of pschological science at the university, says: "Substituting a part of the diet with a similar tasting item that has fewer calories sounds like a common sense approach to lose weight, but there are other psychological functions at work.
"Tastes normally alert the body to expect calories.
"When those calories aren't present, we believe the systems become confused and one of the body's mechanisms to control food inake can become ineffective."