The aim of the current investigations was to examine the effects of a low-carbohydrate high-fat diet (LC-HFD) on body weight, body composition, growth hormone (GH), IGF-I, and body weight regain after stopping the dietary intervention and returning the diet back to standard laboratory chow (CH). In study one, both adolescent and mature male Wistar rats were maintained on either an isocaloric LC-HFD or CH for 16 days before having their diet switched. In study two, mature rats were maintained on either LC-HFD or CH for 16 days to determine the effects of the LC-HFD on fat pad weight. LC-HFD leads to body weight loss in mature rats (P < 0.01) and lack of body weight gain in adolescent rats (P < 0.01). Despite less body weight, increased body fat was observed in rats maintained on LC-HFD (P < 0.05). Leptin concentrations were higher (P < 0.05), and IGF-I (P < 0.01) concentrations were reduced in the LC-HFD rats. When the diet was returned to CH following LC-HFD, body weight regain was above and beyond that which was lost (P < 0.01). The LC-HFD resulted in increased body fat and had a negative effect upon both GH and IGF-I concentrations, which might have implications for the accretion and maintenance of lean body mass (LBM), normal growth rate and overall metabolic health. Moreover, when the LC-HFD ceases and a high-carbohydrate diet follows, more body weight is regained as compared to when the LC-HFD is consumed, in the absence of increased energy intake.