Altered HDL subclasses in endogenous hypertriglyceridemia are not affected by weight reduction.

Reduction of body weight is commonly used to decrease the plasma lipids of patients with primary endogenous hypertriglyceridemia, but the effects of stabilized weight reduction on lipoprotein compositions and distribution are not well known. Since lipoprotein structures are perhaps as important in normal and abnormal metabolism and atherogenesis as are the levels of lipoproteins, we examined the effects of weight loss on the plasma concentrations, compositions, and ultracentrifugal flotation properties of plasma lipoproteins. Nine patients (eight males, one female) with endogenous hypertriglyceridemia and low high-density lipoprotein (HDL)-cholesterol levels who were approximately 130% of ideal body weight were studied during two dietary periods (basal and low weight). Subjects consumed an isocaloric diet for 5 weeks consisting of approximately 15% protein, approximately 45% carbohydrate, approximately 40% fat, approximately 500 mg/d cholesterol, P/S ratio 0.43 (basal), followed by a hypocaloric diet of the same composition, which was eaten for 16 to 52 weeks, until the desired weight was lost (9.6 +/- 3.6 kg). Then patients continued to eat a diet of the same composition lower in calories but sufficient in quantity to maintain their new lower body weights for the final 5 weeks (low-weight period). The last weeks of the basal and the low-weight periods were spent in a metabolic ward. Thus, high and low body weights were known to be stable for at least 5 weeks. Fasting (12 to 14 hours) plasma total triglycerides decreased in all patients (from 328 +/- 204 mg/dL at basal to 185 +/- 77 mg/dL at low weight, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)