It's a well-known diet rule that if you want to stay slim, the secret is to eat a low-calorie diet and exercise regularly.
However, if you snack on and drink low-calorie substitutes, you're more likely to gain the pounds than shift the flab.
Researchers from the Purdue University in Indiana discovered that the taste of fat and sugar causes the body to expect a calorific buzz. But when it doesn't get its desired high-calorie hit, the body gets confused and makes us eat more.
The study came to this conclusion by feeding two groups of lab rats crushed crisps. One group was given a mixture of high-fat and fat-substitute crisps, while the other group was fed only full-fat crisps.
After 28 days, researchers found the animals that ate a diet supplement of fat-substitute crisps gained more weight and fatty tissue than those on full-fat crisps.
"Substituting a part of the diet with a similar tasting item that has fewer or zero calories sounds like a common-sense approach to lose weight, but there are other physiological functions at work," says Professor Susan Swithers from the study.
"These substitutes are meant to mimic the taste of fat in foods that are normally high in fat while providing a lower number of calories, but they may end up confusing the body. Tastes normally alert the body to expect calories, and when those calories aren't present we believe the systems become ineffective and one of the body's mechanisms to control food intake can become ineffective."
"We are looking at an animal model, but there are similarities for humans, and based on what we found, we believe that our findings question the effectiveness of using fat substitutes as part of a long-term weight loss strategy," added co-author of the study, Professor Terry Davidson.
If you're cutting down on your calorie intake but want to do it sensibly, take a look at these healthy low-calorie snacks that don't substitute fat or sugar.