In an ironic turn of events, it seems that fake fat may make you fat instead of help you shed those unwanted pounds. New research challenges the traditional wisdom that foods made with fat substitutes help you lose weight.

Fat substitutes may interfere with the body's ability to regulate food intake and lead to an inefficient use of calories, causing weight gain.

Researchers at Purdue University put two groups of rats on different high and low-fat diets. Half of each group was fed regular Pringles and the other half was fed a mix of regular Pringles and Pringles Light chips; both were fed their usual chow. Pringles Light chips are made with olestra, a fat substitute that has no calories and passes through the gastrointestinal tract undigested.

The surprising results? The rats that ate the high-fat diet and ate both types of chips consumed more food and gained more weight as well as fat tissue than the rats that ate only the high-calorie chips. Moreover, when the potato chips were removed from their diet, they did not lose the extra weight. The news isn't all bad though. The rats that were fed a low-fat diet didn't gain a significant amount of weight.

Fat substitutes may interfere with the body's ability to regulate food intake and lead to an inefficient use of calories, causing weight gain, according to lead researcher and Purdue psychology professor, Susan E. Swithers, PhD. Even though humans and rats have similar biological responses to food, the researchers concede that it is difficult to infer laboratory findings about rats to humans.

Sweet or fatty foods are usually high in calories, and the taste triggers a variety of responses by the body, including salivation and the release of "feel-good" hormones. Fat substitutes can interfere with the response when the body expects to receive a lot of calories but is fooled by a fat substitute.

Swithers along with Purdue psychology professor Terry L. Davidson, PhD, have reported similar results in rat studies regarding the use of artificial sweeteners, weight gain, and increased body fat. While weight gain among Americans has increased dramatically over the past 30 years, so has the use of artificial sweeteners and fat substitutes.

Based on the results of this study and their previous studies, Swithers says that a diet low in fat and calories might be a better way to lose weight than relying on fat substitutes or artificial sweeteners to cut calories.

The study was published online in the American Psychological Association's journal, Behavioral Neuroscience.