Influence of Initial Food Restriction on Subsequent Body Weight Gain and Body Fat Accumulation in Rats

To determine the effect of initial food restriction on subsequent body weight gain and body fat accumulation, rats were restricted to 75, 50, or 25% of the intake of control rats for 1 week and were subsequently pair-fed on a food intake basis to the control rats. As expected, restricted rats gained weight at a slower rate and had less body fat at the end of the restriction period than control rats. Upon refeeding the same amount of food as consumed by the control rats, these rats gained more body fat than control rats. This compensatory fat gain occurred regardless of whether the rats were force-fed twice daily, meal-fed once daily, or allowed to consume the food throughout the day. Both a high-carbohydrate and a high-fat diet produced compensatory fat gain. Compensation was apparent as early as the first week of refeeding and was greater in rats which had been restricted to 50 or 25% of ad libitum intake than in rats less severely restricted. Restricted rats were also refed on a body weight basis. They gained as much weight and fat as the ad libitum fed controls, indicating that the restricted rats were more efficient in converting dietary energy to body fat when refed than rats fed ad libitum continuously. These results suggest that the initial food restriction inherent in many studies involving meal frequency may cause the subsequent increased food efficiency and greater accumulation of body fat often attributed to an alteration in meal pattern. Our studies indicate that meal pattern has a minimal influence on body fat content provided the control animals are pair-fed throughout the entire experiment.