EFFECTS OF AN AMERICAN-HEART-ASSOCIATION STEP-I DIET AND WEIGHT-LOSS ON LIPOPROTEIN LIPID-LEVELS IN OBESE MEN WITH SILENT-MYOCARDIAL-ISCHEMIA AND REDUCED HIGH-DENSITY-LIPOPROTEIN CHOLESTEROL

Reduced plasma concentrations of high-density lipoprotein cholesterol (HDL-C) are a risk factor for coronary artery disease (CAD). In this s tudy, we examined the sequential effects of an isocaloric American Hea rt Association (AHA) step I diet and a hypocaloric AHA step I diet (AH A step I diet + weight loss) on lipoprotein lipid levels in 14 middle- aged and older (60 +/- 6 years, mean a SD) obese (body mass index [BMI ] > 27 kg/m(2)) nondiabetic men with exercise-induced silent myocardia l ischemia (SI) and reduced HDL-C levels (0.85 +/- 0.14 mmol/L). Nine men of comparable age and obesity and with no evidence of exercise-ind uced ischemia that were evaluated longitudinally served as metabolic c ontrols. In men with SI, after 3 months on the isocaloric AHA step I d iet plasma triglyceride (TG) levels decreased by 26% (2.25 +/- 0.66 to 1.67 +/- 0.69 mmol/L, P<.005), cholesterol by 12% (5.24 +/- 0.84 to 4 .62 +/- 0.78 mmol/L, P<.01), and low-density lipoprotein cholesterol ( LDL-C) by 10% (3.40 +/- 0.69 to 3.05 +/- 0.70 mmol/L, P<.01). However, plasma HDL-C levels also decreased by 7% (0.85 +/- 0.14 to 0.79 +/- 0 .13 mmol/L, P<.05). Subsequent weight loss (11 +/- 4 kg) in conjunctio n with the AHA step I diet resulted in an additional decrease of 24% i n TG (P<.005), 10% in cholesterol (P<.05), and 10% in LDL-C (P<.05). P lasma HDL-C levels increased by 8% (P<.01), thereby correcting the dec line seen on the AHA step I diet alone. Postheparin hepatic lipase (HL ) activity decreased with weight loss (P<.005), with no significant ch ange in lipoprotein lipase (LPL) activity. There were no significant c hanges in lipoprotein lipids or postheparin lipolytic activity in the metabolic controls. Therefore, in men with SI, the sequential interven tions of an isocaloric AHA step I diet and an AHA step I diet with wei ght loss decreased plasma TG levels by 44% (P<.0001), LDL-C levels by 18% (P<.0001), and the LDL-C to HDL-C ratio by 19% (P<.005), with no s ignificant change in HDL-C levels. Additional treatment modalities tha t include supervised exercise programs and drug therapy may be warrant ed in older obese subjects whose HDL-C levels do not normalize with di et and weight-loss interventions alone. Copyright (C) 1995 by W.B. Sau nders Company