Survival and body composition of normal and hypothalamic obese rats in acute starvation

Abstract

Female hypothalamic obese rats contained approximately 240% more fat, 10% more protein and 18% more water than did their controls, however ratio total water/fat-free mass remained within normal limits in this frank obesity. At death from starvation, the water, fat-free mass and protein compartments were significantly smaller than those of the controls, the fat compartments were not significantly different. Control rats survived starvation for 16.4 ± 1.3 days, obese rats 42.7 ± 1.8 days (P < .001). The resting metabolic rates of normal and obese rats in the fed state were not different and both fell gradually throughout starvation. The prolonged survival of obese rats is due primarily to their excess reserve of energy and not to alterations in metabolic rate. As in the fed state, hypothalamic obese rats drank less water during starvation than did the controls. This is thought to result from direct interference with hypothalamic elements regulating thirst and the spontaneous consumption of water.