Influence of a liquid diet and meal pattern on body weight and body fat in rats.

Rats weighing 110 to 150 g or 250 g initially were utilized in five experiments to determine the effect of the form of the diet (dry versus liquid) and the pattern of feeding (meal-feeding, force-feeding, nibbling, or ad libitum) on body weight gain and on body fat. A high-carbohydrate, 20% casein or 20% lactalbumin diet was fed for 4 to 8 weeks. Consumption of a diet mixed with an equal weight of water increased weight gain in one of three experiments. Body fat content of the rats was not influenced by addition of water to the diet. Neither force-feeding nor meal-feeding influenced body fat gain provided the respective control rats were pair-fed during the initial adaptation period. Likewise, when rats were pair force-fed to ad libitum fed rats without an initial adaptation meal frequency did not influence body fat gain. When meal-fed rats were switched to ad libitum intake their food intake increased to equal that of rats which had been continuously fed ad libitum; however, the rats which had been switched gained more body fat than did rats continuously fed ad libitum. These results suggest that meal frequency may have a minimal influence on body fat accumulation, but that a shift to a higher level of food intake may cause an increased food efficiency and greater rate of fat deposition than in rats continuously fed the higher level of intake.