How low-calorie fat could still make you gain weight

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Lab tests on rats indicate that commonly used fake fats, which don't get absorbed into the body, may be even less desirable than their side effect of 'anal leakage' makes them sound.

Some readers may remember the advent of fake fats. They were born of the nineties, an era that saw fat as the enemy of all dieters. These fake fats were going to be put in cheeses, ice cream, cakes, and potato chips, freeing up people to eat whatever they liked. Then they caused stomach upset and anal leakage. That, combined with the fact that society moved on on to the low-carb fad diets, took much of the wind out of the sails of the fake fat industry, but the products stay on the shelves as part of the the low-fat versions of popular potato chips and desserts.


Recently, scientists set out to test how well this non-absorbable fat helped people lose weight. They divided a population of lab rats into groups. One group of rats was given a low-fat diet, and one was given a high-fat one. The two groups were then subdivided into groups that were fed full-fat chips, and groups that had full-fat chips one day and fake-fat chips the next.

Despite the fact that the fake-fat has zero calories because it cannot be absorbed by the body, the rats on the combination high-fat and fake-fat diet gained more weight than the high-fat, real-fat rats. This result has qualifications. The rats given the fake-fat consumed more food in total, something dieters may choose not to do. The fats themselves may still play a role in weight gain, though. The scientists running the study believe that some of the gain in fat tissue came from biological reactions. When a person tastes fatty or sweet food, the body has a different response than it does to less high-fat fare. It salivates differently, secretes different hormones, and cues up different metabolic reactions. If a body is geared for a lot of calories, and receives only a few, it could trigger more hunger and a less efficient way of processing the calories that do come, leading to a gain in fat tissue, not a burst of energy.


This process can keep causing trouble even after it's stopped. The rats that were fed a low-fat diet didn't gain a lot of weight no matter what combination of fats they were fed. However, when they were switched to a high-fat diet, the fake-fat rats also ate more and gained more weight than their real-fat compatriots. It apparently doesn't pay to fool the body.

Via the APA.