Effects of fat intake and exercise on serum cholesterol and body composition of rats

Abstract

One hundred and twenty male Wistar rats were obtained at 100 days of age and fed for 50 days a low-fat diet ad lib. to establish high body weight. The rats were then assigned to 8 experimental groups of 15 rats each as follows: 4 groups received a high-fat diet and 4 groups continued to receive the low-fat diet, 2 groups on each diet being fed ad lib. and 2 groups were fed 65% of ad lib. intake; 1 of the 2 groups receiving each diet at a set calorie intake was forced to swim two 30-min. periods/day and the other group remained sedentary. Relative body composition was altered only by exercise at the ad lib. level of calorie intake. Feeding the high-fat diet at the restricted calorie intake significantly reduced liver weight, but this was due to a change in weight of the gastrointestinal contents. Exercise resulted in smaller perirenal and epididymal fat pads, but larger livers, hearts, and adrenals than those found in sedentary animals. Substituting the high-fat for the low-fat diet caused a relative increase in adrenal size and the size of the perirenal and epididymal fat pads. Serum cholesterol tended to be higher in rats fed the high-fat diet and was significantly elevated in calorie-restricted animals forced to exercise.