low dosages of exogenous growth hormone and its effect on growth in an animal model of suboptimal nutrition in a previous study weight gain insulin growth factor1 igf1 and insulin growth factor binding protein3 igfbp3 were increased in rats fed suboptimal levels of energy and administered 01 mg100 g of body weight of recombinant human growth hormone rhgh our objective was to determine whether these anabolic effects were still obtained with lower dosages of rhgh in similarly fed rats three groups of male prepubertal spraguedawley rats were administered rhgh and three groups of similar rats were given normal saline solution daily 005 mg100 g of body weight subcutaneously all rats were fed a balanced 11 carbohydratefat ratio diet for 4 wk restricted rats within each treatment were pair fed 80 and 60 ad libitum daily body weight food intake and efficiency were recorded after 4 wk serum igf1 and igfbp3 body fat fatfree mass and total body water were determined total weight gain and serum igfbp3 were significantly higher with a tendency for increased body fat in rats treated with rhgh and fed at 60 ad libitum however within each treatment energy restriction caused decreased body fat and total body water these results suggest that lower dosages of rhgh provide anabolic effects during suboptimal energy intake