A direct anabolic effect of progesterone in the intact female rat

Rats implanted with progesterone gained weight more rapidly than controls and had a greater percentage of total body fat. The dietary intake of hormone-treated animals was restricted to control levels. The food was supplied in small quantities at regular intervals over a 24-h period with the aid of automatic feeding machines. The observed changes in body weight and composition are therefore not related to either an increased intake of energy or a change in the pattern of feeding after implantation.