Background A low-carbohydrate diet remains controversial, especially in patients with arteriosclerotic heart disease. Hypothesis: This study was undertaken to evaluate the effect of a low-carbohydrate diet on the lipid levels in obese patients with known arteriosclerotic heart disease on chronic statin therapy. Methods: Thirty-eight overweight patients with angiographically documented arteriosclerotic heart disease were followed in a private cardiology practice setting. All patients were undergoing stable statin therapy. Patients received a 15-min consultation and a 4-page pamphlet explaining a low-carbohydrate diet; no other diet instruction was given. Patients were followed weekly for 2 weeks, then monthly for 3 months, then every third month. A fasting finger stick lipid panel (cholesterol, high-density and low- density lipoprotein [HDL/LDL], triglycerides, and glucose) was obtained with each visit and patients were weighed in street clothes. Results: The 38 Patients were followed for a average of 11.8 months (range 6-22 months). Average body mass index declined from 33.5 kg/m(2) before to 27.9 kg/m(2) at the end of the study. Weight loss averaged 31 lbs (range 16-107 lbs). Triglyceride levels were lowered by 29.5%, HDL raised by 17.6%, and cholesterol decreased by 8.4%. The cholesterol/HDL ratio changed from 5.31 to 3.78 and LDL cholesterol decreased by 5%. Conclusion: The addition of a low-carbohydrate diet for overweight patients with known coronary artery disease undergoing stable statin therapy causes significant weight loss and a favorable change in the lipid panel.