Unexpected decrease in plasma high density lipoprotein cholesterol with weight loss.

High density lipoprotein (HDL) cholesterol is inversely related to coronary heart disease prevalence. Despite the fact that obese patients have lower plasma HDL-cholesterol concentrations, there are few prospective studies on the effect of weight loss on HDL-cholesterol. Consequently, plasma lipoprotein levels were measured in 15 obese females before and after a 10 week weight loss program. Mean weight loss was 8.6 +/- 3.9 kg (P less than 0.001). Total plasma cholesterol and low density lipoprotein-cholesterol did not change significantly. Plasma triglyceride levels decreased (P less than 0.05) as did HDL-cholesterol (P less than 0.02). A subgroup of 11 of the subjects had repeat lipid measurements 8 months after the start of treatment. Mean weight loss at this time was 12.8 +/- 0.8 kg (P less than 0.01). No subject had returned to her pretreatment weight but mean weight loss was not significantly different from the 10 week value. At 8 months all lipid values, including HDL-cholesterol, had returned to their pretreatment value. By multiple regression analysis HDL-cholesterol decreased with increasing relative weight but also decreased with increasing rate of weight loss. These results suggest that negative caloric balance produces a decrease in HDL-cholesterol that in prospective studies may obscure the inverse relationship between HDL-cholesterol and indices of obesity.