Effect of age and duration of meal-eating on body composition and on lipogenesis and cellularity of adipose tissue in male rats.

Several studies indicate that in rats changing the rhythm of feeding from nibbling to meal-eating results in hyperlipogenesis and higher body fat deposition. Among the factors influencing this phenomenon, the effects of age and duration of treatment are not yet clear. Male rats of 4, 6, 12 and 18 weeks have been meal-fed (two 1-hour meals per day) for 5, 10, 20 and 30 days. Pair-fed Nibblers were used as controls. Adipocyte diameters and number from epididymal adipose tissues were determined, and lipogenesis measured my glucose-U-14-C incorporation into lipids. The results show that cellularity, glucose-U-14-C incorporation into adipocyte lipids and CO2 and body fat deposition are not affected by short-term meal-eating treatment in growing animals. In the adult rats, only after 30 days do the parameters studied show significant higher values in the meal-eating animals. The results are discussed in view of the possible interrelationships among the different factors influencing animal response to modifications in feeding frequency.