| Dietary macronutrient composition plays a critical role in health and disease. The contribution of dietary carbohydrate source in the development of obesity and related diseases is often given minimal attention. The present studies demonstrate that both quantitative and qualitative changes in dietary carbohydrate influence body composition and adiposity in a rodent model of diet-induced obesity. High-fat, carbohydrate-free diets, fed ad libitum or with energy restriction, attenuated weight gain and adiposity by increasing energy efficiency and blunting expression of fatty acid synthase, a key enzyme in de novo lipogenesis. These effects were independent of significant changes in plasma insulin levels, compared with semi-purified standard rodent chow. Moreover, the addition of a modest level of sucrose to the high-fat diet completely reversed the effects of carbohydrate restriction, resulting in a significant increase in body weight and adiposity.; In a separate series of experiments, we evaluated the effects of ad libitum or energy restricted (70% of ad libitum) high-fat diets, varying in carbohydrate source on adiposity in aP2-agouti transgenic mice. In the context of an energy restricted diet, animals consuming diets shown to result in lower postprandial blood glucose levels (ROLL and MUNG) reduced adipose tissue accumulation in the perirenal and retroperitoneal and resulted in smaller adipocytes compared with diets evoking greater postprandial blood glucose excursions.; In ad libitum fed animals, the expression of lipogenic enzymes in the liver and selected adipose tissue depots was significantly enhanced by consumption of a high-fat, sucrose-rich diet. Expression of genes of fatty acid oxidation was enhanced in the muscle of animals consuming the low-glucose response diets. These data suggest that dietary carbohydrate source modulates adipose tissue accumulation and body weight by shifting substrate utilization in favor of lipid oxidation in skeletal muscle as well as reducing lipogenesis in visceral adipose tissue. |
