Metabolic responses to episodes of partial dietary restriction in undernourished Wistar rats

Wistar rat pups raised in large litters (LL) and small litters (SL) prior to weaning had access to ad libitum dietary intakes up to the age of 90 days. At 90 and again at 180 days they were partially diet restricted for a period of 15 days. Body weights, resting metabolic rates (RMR) and capacity for nonshivering thermogenesis (NST) was evaluated prior to, during and after the period of energy restriction. Responses were compared with 180 day rats from both groups who had been diet restricted for the first time at 180 days. Body weight losses were greater in the latter group. Groups of rats exposed to dietary restriction once, had higher body weights than rats of identical ages who had not been restricted. RMR decreased in all groups during restriction. However, reductions in NST were seen only in nutritionally deprived animals and in well-nourished controls who were partially restricted once. Changes in NST contribute to metabolic efficiency seen during episodic dietary restriction.