The effects of high fat feeding during one cycle of reproduction consisting of pregnancy, lactation and recovery on body composition and fat pad cellularity in the rat.

The changes in adipose depot weight, cell size, cell number and body composition during pregnancy, lactation and recovery were studied in Osborne-Mendel rats fed standard or high fat diets. Rats were killed on day 21 of pregnancy, after 21 days of lactation, and after 21 or 22 days of a postlactational recovery period. Nonpregnant control groups were killed at the beginning and at the conclusion of the experimental period. The high fat-fed, mated group was always fatter than similarly treated animals fed standard diets throughout pregnancy and lactation. However, by the end of the recovery period, carcass composition of the animals fed high fat or standard diets and the nonpregnant groups were not statistically different. The weight of the parametrial, retroperitoneal and subscapular depots was higher in the high fat-fed animals at the end of the recovery period, and in the latter two pads, this increase was statistically significant. Thus, despite the extensive lipid mobilization that occurs during lactation, the high fat-fed animals appear to be predisposed to postpartum obesity.