Fat substitutes linked to weight gain

Friday, 29 July 2011 09:45

You might think that reaching for foods made with a fat substitute will help you keep your weight down, but a recent study by Purdue University has discovered just the opposite. Researchers found that rats fed nonfat potato chips made with Olestra — a fat substitute from Proctor & Gamble — actually gained more weight than rats that ate regular, high-fat potato chips.

Researchers note that when your body tastes sweet or fatty foods — even if those foods don't contain the real thing — it sets a series of metabolic and hormonal responses into action as the body begins to prepare to digest a large number of calories. When the calories don't actually arrive, it confuses the body and disrupts the normal metabolic process.

"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," said Susan E. Swithers, professor of psychological sciences at Purdue and lead researcher of the study. "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."

In the study, which was published in the June issue of Behavioral Neuroscience, rats were fed crushed potato chips in addition to their regular diet. The rats received either high-fat potato chips or a mixture of high-fat chips and chips containing Olestra, which passes through the body undigested. Rats who received the chips with Olestra gained more weight and developed more fatty tissue over the course of 28 days. In addition, the rats in this group failed to lose weight even after the chips were removed from their diet.

In earlier studies, Purdue researchers discovered that rats fed artificial sweeteners were more likely to overeat. They believe that both artificial sweeteners and fat substitutes cause a disruption in the body's normal digestive process.

"When the mouth tastes something sweet or fatty it tells the body to prepare for calories, and this information is key to the digestive process," Swithers said. "Based on this data, a diet that is low in fat and calories might be a better strategy for weight loss than using fat substitutes."