Effect of high fat vs. high carbohydrate feeding on the development of obesity in weanling ob/ob mice.

Mice with hereditary obesity (ob/ob) were fed isocaloric, isoprotein diets with varying proportions of carbohydrate-to-fat from the time of weaning to 18 weeks of age. Body weight, plasma glucose,and plasma insulin were determined at frequent intervals; body lipid and pancreatic insulin were determined at termination. Obesity developed when only carbohydrate was provided as caloric source (and in the presence of essential fatty acid deficiency), but obesity was greatly enhanced when 5% fat was added. Obesity also developed in the absence of dietary carbohydrate, even though hyperinsulinism was significantly reduced by this regimen. It is concluded that 1) both enhanced storage of dietary fat and lipogenesis contribute to obesity, the former more so than the latter; 2) the degree of hyperinsulinism does not determine the degree of obesity; 3) the development of hyperinsulinism does not require stimulation by exogenous oral carbohydrate.