DIET-INDUCED OBESITY IN MICE CAN BE TREATED WITHOUT ENERGY RESTRICTION USING EXERCISE AND/OR A LOW-FAT DIET

Diet-induced obesity was treated with a high carbohydrate, low fat diet and/or increased voluntary exercise in mice. All mice had free access to food and water during the two stage experiment. In Stage 1, 20 female mice were fed a high carbohydrate diet and 50 were made obese by consumption of a diet providing 40.8% of energy from fat. At the end of Stage 1, obese mice had significantly greater body fat stores (22.9 +/- 0.9 g/100 g body wt) than mice fed the high carbohydrate diet (12.9 +/- 1.2) (P < 0.001), yet there was no significant difference in lean body mass. In Stage 2, half of the mice were given activity wheels to increase their voluntary activity and half of the obese mice were switched to a high carbohydrate diet resulting in six groups with treatment designations of obese or lean; exercise or nonexercise, and carbohydrate or fat diets. Body fat was significantly reduced by consumption of the high carbohydrate diet (P < 0.005) and by exercise (P < 0.001), but neither treatment affected lean body mass. Exercising mice consumed significantly more energy than nonexercising mice, yet experienced a decrease in body fat and energy stores. The final fat concentration (g/100 g body wt) of each experimental group was as follows: lean, nonexercising mice fed the carbohydrate diet, 13.6 +/- 1.9; lean, exercising mice fed the carbohydrate diet, 7.1 +/- 1.5; obese, nonexercising mice fed the fat diet, 23.7 +/- 2.9; obese, nonexercising mice fed the carbohydrate diet, 15.1 +/- 2.5; obese, exercising mice fed the fat diet, 9.7 +/- 0.9; and obese, exercising mice fed the carbohydrate diet, 7.0 +/- 1.0. Exercising mice regulated energy intake in relation to physical activity and fat stores. This research suggests that obesity induced by a high fat diet can be treated without energy restriction by exercise and/or high carbohydrate, low fat diets.