Fat Substitute Causes Weight Gain in Rats Eating High-Fat Diets

Olestra is a commonly used substitute for fat. It tastes similar to fat, but contains less calories. It is thought to help in the prevention of obesity. Many studies on sugar substitutes, such as saccharin, have shown that sugar substitutes can increase body weight. In the present study, the researchers examined the consequences of consuming fat substitutes. In laboratory tests performed on rats, it was demonstrated that rats that consumed foods with fat substitutes showed a considerable increase in body weight and adiposity compared to those that did not consume fat substitutes.

Consumption of food with low calorie content is one of the strategies adopted to decrease the occurrence of obesity. This is done either by diluting the food with bulking agents or by substituting high-calorie substances with low-calorie ones. However, in contrast to this belief, sugar substitutes are found to promote obesity. This is thought to occur due to an imbalance in the physiological and hormonal response to the consumption of a high-calorie diet. So far, very few studies have assessed the effects of consumption of fat substitutes such as olestra. This study, which was done on rats, examined the association between the consumption of olestra and gain in body weight.

* This study was conducted on 31 rats that were divided into four groups. At the beginning of the experiment, their average weight was 350 g. Before commencing the experiment, the rats were fed on a standard chow diet for five days.
* For 28 days, along with the standard chow diet, 15 rats were given high-fat potato chips. The rest of the rats were fed with high-fat chips along with chips containing fat substitutes (olestra) together with the standard chow diet.
* Later on, half of the rats in each group received a high-fat chow diet and the remaining half received a standard chow diet for 16 days.
* At periodic intervals, the body weight of rats, amount of food consumed by them, and their body composition (body fat and lean body mass) were assessed.

* The rats that consumed chips prepared in olestra and then later consumed a standard chow diet did not gain significant weight.
* In contrast, the rats that were maintained on a high-fat diet (olestra and high-fat chips) showed a significant increase in body weight compared to those that were given the high-fat chips only. A study of the body composition showed that “animals on the high fat diet given the olestra plus high fat chips had significantly more fat than animals given only the high fat chips.”
* There was no reduction in body weight even after the discontinuation of the chips diet, containing olestra.
* An analysis of the total food consumption showed that the total calorie consumption was significantly high in rats that consumed olestra and high-fat chips.

This study has disproved the popular belief that low-calorie fat substitutes help in combating obesity. On the contrary, this study has shown that fat substitutes, such as olestra, lead to increase in food consumption, thereby increasing body fat. Whenever a person consumes a calorie-rich diet, hormonal secretions, salivation, and other physiological responses prepare the body for handling the high load of calories. When substitutes of fats or sugars are consumed instead, there is a deregulation in the body’s ability to react to the intake of high calories, ultimately leading to a continuous craving for food despite the consumption of adequate calories. The authors write that the findings of the present study call into question the conventional wisdom that reduction in adiposity will necessarily follow from altering the energy density of foods by introducing low-calorie substitutes.

Note: No Shortcomings/Next steps have been discussed in the article.

For More Information:
Fat Substitutes Promote Weight Gain in Rats Consuming High-Fat Diets
Publication Journal: Behavioral Neuroscience, 2011
By Susan E. Swithers; Sean B. Ogden; Purdue University, West Lafayette, Indiana

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