Introduction: Dietary lipid profile is emerging as an important determinant of successful weight loss and coronary risk reduction in people who are overweight. Energy reduction has been the mainstay of weight loss interventions, however weight maintenance is emerging as another viable strategy. Methods: We used a randomised controlled trial design to study the effects of maintaining usual energy intake, but manipulating dietary lipid profile in a group of 64 overweight (BMI>25), otherwise healthy, subjects. For the intervention group, energy intakes were calculated from multiple 3 day diet diaries, and saturated fat was replaced with MUFA to 50%E by adding macadamia nuts to the diet. Both control and intervention groups received advice on national guidelines for physical activity and adhered to the same protocol for diet diary record keeping and trial consultations. Anthropometric and clinical measures were taken at baseline and at 10 weeks. Data were entered into SPSS version 15.0 and statistical differences were detected by paired t-test analysis. Results: Significant (p<0.05) reductions in mean HDL levels occurred in both groups (1.36 to 1.20 and 1.50 to 1.38mmol/L, respectively for control and intervention). In the intervention group, these changes were accompanied by significant (p<0.05) reductions in mean total cholesterol (5.2 to 4.9 mmol/L) and mean waist circumference (99.2 to 96.9cm). No significant changes were noted for blood pressure, BMI or CHD inflammatory markers. Conclusion: In groups where adherence to dietary energy-reduction is poor, isoenergetic interventions which address CHD risk factors other than body weight may be beneficial.