Energy balance and hypothalamic effects of a high-protein/low-carbohydrate diet

Abstract

Diets high in fat or protein and extremely low in carbohydrate are frequently reported to result in weight loss in humans. We previously reported that rats maintained on a low-carbohydrate–high fat diet (LC–HF) consumed similar kcals/day as chow (CH)-fed rats and did not differ in body weight after 7 weeks. LC–HF rats had a 45% decrease in POMC expression in the ARC, decreased plasma insulin, and increased plasma leptin and ghrelin. In the present study we assessed the effects of a low-carbohydrate–high-protein diet (HP: 30% fat, 65% protein, and 5% CHO) on body weight, caloric intake, plasma hormone levels and hypothalamic gene expression. Male rats (n=16) were maintained on CH or HP for 4 weeks. HP rats gained significantly less weight than CH rats (73.4+/−9.4 and 125.0+/−8.2 g) and consumed significantly less kcals/day (94.8+/−1.5 and 123.6+/−1.1). Insulin was significantly reduced in HP rats (HP: 1.8+/−0.6 vs. CH: 4.12+/−0.8 ng/ml), there were no differences between groups in plasma leptin and plasma ghrelin was significantly elevated in HP rats (HP: 127.5+/−45 vs. CH: 76.9+/−8 pg/ml). Maintenance on HP resulted in significantly increased ARC POMC (HP: 121+/−10.0 vs. 100+/−5.9) and DMH NPY (HP: 297+/−82.1 vs. CH: 100+/−37.7) expression compared to CH controls. These data suggest that the macronutrient content of diets differentially influences hypothalamic gene expression in ways that can affect overall intake.