Effects of 16 mo of verified, supervised aerobic exercise on macronutrient intake in overweight men and women: the Midwest Exercise Trial

Background: It is commonly believed that moderate aerobic exercise leads to changes in diet composition, specifically, an increase in carbohydrate intake at the expense of fat intake. Objective: The goal was to determine the effects of a supervised, long-term program of exercise on the macronutrient intake of previously sedentary, overweight and moderately obese men and women. Design: Participants (n = 74) were recruited from the university and surrounding communities and were randomly assigned to the exercise or control group. Exercise of moderate intensity was performed for 45 min/d, 5 d/wk, under supervision. Diet intake was ad libitum and was measured for energy and macronutrient composition at baseline and at 5 other occasions across the 16-mo study by use of weighing and measuring techniques. Each measurement consisted of a 2-wk period of direct measurement in the university cafeteria. Food consumption outside the cafeteria during the 2-wk periods (ie, snacks) was measured by multiple-pass 24-h dietary recall procedures. Results: There were no significant differences for men or women between the exercise and control groups from baseline to 16 mo in fat, carbohydrate, or protein intake expressed as grams or as percentages of total energy intake. Conclusion: Sixteen months of exercise of moderate intensity does not measurably alter the macronutrient intake of young adults.