Washington, June 23 (IANS) Beware of fat substitutes in popular snacks - instead of helping you shed weight, they may promote weight gain, says a new 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," said Susan E. Swithers, professor of psychological sciences at Purdue.

"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," Swithers added, reports the journal Behavioral Neuroscience.

In this study, lab rats received crushed potato chips as a dietary supplement, and then they were divided into two groups that were given either a low-fat chow diet or a high-fat chow diet, according to a Purdue statement.

These groups were each split into two smaller groups. One group on each diet was fed a mixture of high-fat chips and the fat-substitute chips, containing olestra, which is a synthetic fat with no calories, while the other group received only regular high-fat chips.

The chips were provided for 28 days. Rats maintained on the high-fat chow diet gained more weight and developed more fatty tissues when they were given fat-substitute chips compared to the animals that ate only regular high-fat chips.

"What's interesting here is that weight gain occurred regardless of when the rats consumed the low-calorie, fat-substituted chips," Swithers said.

"Our findings question the effectiveness of using fat substitutes as part of a long-term weight loss strategy," said study co-author Terry L. Davidson, professor of psychological sciences at Purdue.