OBJECTIVE: To test t he hypothesis that increased consumption of foods in rich in starch, such as breakfast cereals, will enable a substantial reduction in the percentage dietary energy derived from fat. DESIGN: Parallel experimental design, with matched subjects allocated randomly to an intervention or a control group. SETTING: Free-living subjects (mean age 20 y), undergraduate students at a college for higher education. SUBJECTS: Sixty-two enrolled, 59 completed the study; 7 d weighed intakes at baseline, 4 weeks and 12 weeks. INTERVENTION: The intervention group were required to eat 60 g breakfast cereal daily with semi-skimmed milk. Pre-weighed portions of three types of cereal were distributed without charge at the beginning of each week of the study; subjects were reimbursed for the cost of milk used. No other dietary advice was given. RESULTS: At baseline, total energy intake and percentage energy from macronutrients was very similar in both the intervention and control group. After four weeks of intervention there was a significant reduction in % energy from fat (-5.4%) in the experimental group, maintained at the 12 weeks follow-up. There was a corresponding rise in energy from CHO: a significant increase of 5.5% after four weeks had reached 6.5% by 12 weeks. Total energy remained virtually unchanged, indicating a replacement of fat energy by carbohydrate energy. These changes were not found in the control group. CONCLUSIONS: A simple dietary intervention to increase consumption of breakfast cereal led to a 5% reduction in % dietary fat energy, with a beneficial effect on micronutrient intakes. The results support the case for positive advice to increase consumption of complex carbohydrate, as a strategy for dietary fat reduction in the wider population.