This randomised controlled trial examined anthropometric changes and cardiovascular benefits of six months of weight management in 110 free living women, aged 18-68 y and BMI 25-50 kg/m2, who received 1200 kcal/d diet treatments of either high (58% energy, n = 57) or low (35% energy, n = 53) carbohydrate (CHO) content. Body weight, plasma total, HDL and LDL cholesterol, triglyceride and blood pressure were measured. Examination at three months showed women on high CHO lost (mean +/- s.e.m) 4.3 +/- 0.5 kg and those on low CHO lost 5.6 +/- 0.6 kg of body weight. Changes in risk factors did not significantly differ between the two diet treatments throughout the study. However those on high CHO diets significantly lowered their plasma total cholesterol by 0.33 mmol/l (95% CI: 0.10, 0.55), LDL cholesterol by 0.23 mmol/l (0.02, 0.43) and HDL cholesterol by 0.05 mmol/l (0.03, 0.10), while women on low CHO diets lowered only plasma triglyceride by 0.28 mmol/l (0.08, 0.48). Blood pressure did not change significantly on either diet. After six months, women on high CHO lost 5.6 +/- 0.8 kg and those on low CHO lost 6.8 +/- 0.8 kg. On the high CHO diet, total cholesterol remained significantly below the baseline value at 0.34 mmol/l (0.13, 0.56), triglyceride was significantly lowered by 0.27 mmol/l (0.10, 0.45), and HDL cholesterol returned to the baseline value. On the low CHO diet, triglyceride remained the only risk factor to be significantly improved. A subgroup of 46 postmenopausal women lost significantly (P < 0.05) more weight on the low CHO diet than high CHO diet. In conclusion, these results provided some support for preferring a high CHO diet to a lower CHO approach in weight management, from the point of view of risk reduction, but do not indicate a consistently more rapid weight loss with either diet.