The effect of controlled feeding conditions on the metabolic characteristics of rats

To evaluate the effect of feeding conditions on blood glucose, insulin and free fatty acid concentrations, rats were maintained on a 2-hr feeding/22-hr fasting (regular-fasted) schedule for 4 weeks. The animals were then subjected to glucose or insulin loads immediately prior to the usual meal time. Animals fasted for only 22 hr (single-fasted) just before the experiments, and rats having access to food ad lib were similarly loaded and tested. The results demonstrate that the regular fasting regime induces certain metabolic alterations well described in the literature for the single-fasted-period to become more pronounced, specifically, a reduction in insulin secretion and a probably increase in peripheral responsiveness to this hormone. In addition, glucose loading was more effective in lowering plasma free fatty acid concentration in rats restricted to a regular fasting scheme.