Abstract
The long-term consequences of early insulin-induced obesity were investigated in two experiments: the first involving 45 female rats and the second 55 males. There was, in both experiments, a prolonged suppression of weight gain following the termination of injections in insulin treated rats. Experimental rats defended this lower body weight even when placed on a high-fat, sweetened diet. In Exp. 2 measures of food and water, intake obesity as measured by the Lee Index, and energy efficiency were taken. Insulin-treated rats consumed a greater number of kcals during injections but fewer than controls during the 14-day resting phase and the 28-day dietary manipulation. The insulin group was more obese than the control group at the end of injections but between-group differences were lost following the resting phase and the dietary manipulation. During injections, experimental rats and controls were approximately equal in their energy efficiency, but insulin-treated rats were significantly less efficient during the second and third phases of experimentation. The results were discussed in terms of hypothesized effects of insulin injections on diet-induced thermogenesis.
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