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Fat substitutes in food could backfire, leading to obesity

Kathleen Blanchard's picture
Fat substitutes, olestra

Research suggests foods with fat substitutes, like the kind used in low calorie potato chips, could lead to weight gain. Cutting calories and choosing foods that are naturally low in fat, may be a better weight loss strategy than consuming foods with fat substitutes like olestra.

The findings, say Purdue researchers, challenges conventional wisdom. Susan E. Swithers, PhD, the lead researcher and a Purdue psychology professor says, “Our research showed that fat substitutes can interfere with the body's ability to regulate food intake, which can lead to inefficient use of calories and weight gain.”

In the study, researchers fed rats a low fat or high fat chow diet. Half were given Pringles high calorie potato chips. The remaining half was fed Light Pringles chips with olestra some days, and on other days high fat and calorie Pringles.

Rats given the high fat diet and both types of Pringles (Light and high fat), gained more weight and more body fat compared to those only given high fat Pringles. They also consumed more food. The researchers say even after the chips were removed from the diet the rats were unable to lose weight.

Dr. Swithers says, though it’s difficult to say fat substitutes in food would trigger the same type of pattern in humans, "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."

Fat substitutes might fool the body's hormones, producing weight gain

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The authors suggest low calorie foods that are sweetened or taste fatty can trick the body into expecting high calories.

The body’s response to sweet foods and higher fat is salivation, secretion of hormones and other metabolic responses. Restricting calories can also slow metabolism, slowing down weight loss efforts.

The authors write, ... we found that even after the opportunity to consume the fat substitutes had been suspended, differences in weight gain and adiposity were maintained. Animals did not lose the extra weight or fat when they were no longer consuming the chips. This
outcome is also similar to that obtained with high intensity sweeteners (Swithers et al., "2009 ").

Those already on a high fat diet gained more weight from eating potato chips containing the fat substitute olestra, leading the authors to conclude eating foods that are naturally low in fat may be a better weight loss strategy overall.

The study does not show for certain that fat substitutes in food leads to weight gain in humans, but it did in rats. The findings also showed the rats that ate a low fat diet did not gain weight with either low fat or regular high calorie, fattening chips. Olestra, shown in the image, is a synthetic fat substitute that passes through the body undigested and is used to provide foods with the same flavor as calorie dense fatty foods. It is made from edible oils and sucrose.

"Fat Substitutes Promote Weight Gain in Rats Consuming High-Fat Diets"
Susan E. Swithers, PhD, Sean B. Ogden, and Terry L. Davidson, PhD, Purdue University
Behavioral Neuroscience, Vol. 125, No. 4

Image credit: Wikimedia commons
Author: Targul

Updated 8/31/2014