Effects of diet on feeding and body weight regulation during pregnancy and lactation in the golden hamster (Mesocricetus auratus).

The hypothesis was tested that the weight loss shown by lactating hamsters constitutes a "regulated" weight loss. The results support the hypothesis: Prefattened overweight hamsters lost more weight from the time of mating to the end of lactation than did unmanipulated controls. However, the weight loss during lactation was reduced by giving hamsters access to a high-fat diet, a result indicating that a portion of the lactational weight loss may also be regulated by the diet provided. When lactating hamsters were given access to a fractionated diet consisting of pure fat, pure carbohydrate, or 45% protein, they increased their proportional intake of both protein and fat but not of carbohydrate. These studies show that hamsters differ from rats in their pattern of energy regulation during pregnancy, lactation, and the postsuckling period. Reasons for these species differences are discussed.