The Role of Exercise in Modulating the Impact of an Ultralow-fat Diet on Serum Lipids and Apolipoproteins in Patients with or at Risk for Coronary Artery Disease

Background: Ultralow-fat diets are known to reduce high-density lipoprotein cholesterol (HDL-C) levels. In the setting of a multicomponent lifestyle intervention program, relationships between exercise variables and HDL-C levels were examined to determine whether exercise moderates this dietary effect on serum lipids and apolipoproteins.

Methods: We performed a 3-month, prospective, nonrandomized lifestyle intervention study (< or = 10% dietary fat; aerobic exercise [180 min/wk], group support, and yoga [60 min/day]) in 120 subjects with or at risk for coronary artery disease.

Results: After 3 months, dietary fat intake was reduced to 8.7% +/- 2.6% of total intake and the median weekly exercise time was 194 minutes. High-density lipoprotein cholesterol levels decreased by 8.3 +/- 11.3 mg/dL (P < .001), and triglyceride levels increased by 17.6 +/- 102.7 mg/dL (P = .026). A small dense low-density lipoprotein cholesterol (LDL-C) phenotype emerged indicated by a 13.8% LDL-C reduction accompanied by only a 2.3% reduction in apolipoprotein B levels (P = .064). Among subjects with exercise amounts less than those of the group median, HDL-C reductions were greater in those with more than (-13.5 +/- 16.0 mg/dL) versus less than (-2.5 +/- 7.5 mg/dL) the median reductions in fat intake (P = .026). Even among subjects who exercised > 194 min/wk, HDL-C was reduced compared with baseline (-7.4 +/- 7.9 mg/dL, P < .001).

Conclusions: An ultralow-fat diet as a component of a comprehensive lifestyle intervention induces reductions in HDL-C and the emergence of a dyslipidemic lipid profile. Aerobic exercise only partially mitigates this effect.