Differential changes in body composition during growth and progesterone treatment in intact female rats.

Female rats implanted with progesterone gained weight more rapidly than control animals and had a greater percentage of total body fat. The proportion of fat in the carcase of control animals also increased as they gained weight. Comparison of progesterone-treated rats with a group of weight-matched controls demonstrated that the effects of progesterone treatment on fat deposition exceeded those which would be expected to accompany their accelerated growth. Excess fat was deposited at the expense of the protein component of fat-free solid.