Monosaccharide-enriched diets cause hyperleptinemia without hypophagia

To determine the effect of monosaccharide-enriched diets on plasma leptin a nd food consumption, body weight, food intake, and serum glucose, insulin, and leptin concentrations were measured in rats maintained on a 10-d course of 60% glucose or 60% fructose diet. The serum leptin concentration in rat s fed a high-glucose diet (7.60 +/- 0.6 ng/mL) or a high-fructose diet (5.1 2 +/- 0.8 ng/mL) was significantly increased compared with that in control rats (2.45 +/- 0.10 ng/mL; P < 0.001). To ascertain that the observed effec t was related to hyperinsulinemia, a group of rats were infused with exogen ous insulin or rendered insulin resistent with a high-fat diet. When hyperi nsulinemia was induced with exogenous infusion, the serum leptin was increa sed (5.56 +/- 0.23 ng/mL; P < 0.001). High-fat feeding was associated with increased serum leptin (12.1 +/- 1.4 ng/mL) and insulin levels. The increas ed serum leptin concentration was not associated with decreased food intake . We conclude that monosaccharide-enriched diets, probably through hyperins ulinemia or relative or absolute insulin resistance, cause hyperleptinemia, which does not appear to change feeding behavior. Nutrition 2000;16:439-44 1. (C)Elsevier Science Inc. 2000.