Moderate alcohol intake is frequently associated with an elevated concentration of high-density lipoprotein (HDL), which is one of the potential causes for the relative decrease in cardiovascular risk reported in moderate drinkers. Conversely, low HDL concentrations, particularly HDL2, in obese subjects may be a risk factor. The effect of 30 g alcohol daily (wine) during 14 days following a period of abstinence was studied in seven normolipidemic obese subjects (body mass index [BMI], 30 +/- 1.7 kg/m2) compared with seven normoponderal controls (BMI, 22 +/- 1.2 kg/m2). Alcohol caused apolipoprotein (apo) AI and apo AII concentrations to increase in all controls by 12% and 16% (P less than .05), but not in obese subjects. Lipoprotein (Lp) AI HDL particles (without AII) were initially in the same proportions in the two groups. Their increase in controls only (P less than .03) was not matched by an increase in HDL2 in all subjects. In obese subjects, neither Lp AI nor HDL2 were increased by alcohol, but their HDL-triglyceride (TG) contents, initially elevated, were normalized. Cholesterol ester (CE) transfer activity was not different in controls and obese subjects during abstinence (105.7 +/- 40.8 v 104.8 +/- 34.5 mmol/mg protein/h). It was notably depressed by alcohol in controls (74.2 +/- 27.4, P less than .002), but not in obese subjects.(ABSTRACT TRUNCATED AT 250 WORDS)