Some Effects of Caloric Restriction and Deprivation on the Obese Hyperlipemic Rat

Abstract

To explore the nature of the genetic obesity in rats of the obese hyperlipemic strain (designated as “fatties”), we studied rates of deposition and of depletion of adipose tissue stores under varying conditions of food intake and stage of growth. When totally starved, young fatties survived until all visible fat stores were exhausted; their low water consumption indicated that they were metabolizing principally fat. Control non-obese rats died much earlier, after exhausting their much smaller fat stores. Controls receiving a diet of fat had survival rates comparable to those of fatties. Terminal weights of all rats were comparable. Adult fatties showed no abnormalities in response to 1, 2 or 7 days of fasting. Young fatties pair-fed to normal sibs for 14 days, with a 40% reduction in weight gain, grew abnormally in that they laid down more fat, and less muscle and bone, than the controls. These fatties finished the experiment as obese as they were at the start. Fat, muscle and bone gains were estimated from gains in representative fat pads and muscle and from the increase in length of a long bone.