The purpose of this study was to determine if the food exchange system allows subjects' nutrient intake to remain at recommended levels during a weight-loss program.
Subjects in an intervention were prescribed an energy-restriction diet and exercise program lasting 32 weeks, and nutrient intake was measured prestudy and after 12, 16, and 32 weeks.
Healthy but overweight and obese premenopausal women (n = 219) were recruited at 6 university sites into community-based weight loss programs. One hundred fifteen women completed all aspects of the study.
Energy intake was set at 0.8 x resting metabolic rate (RMR) for weeks 1 through 12, 1.0 x RMR for weeks 13 through 20, and 1.2 x RMR for weeks 21 through 32. Energy intake was based on food exchange tables, with the number of food exchanges adjusted to encourage a distribution of 55% carbohydrate, 30% fat, and 15% protein. Subjects increased their daily walking distance to 3.2 km above prestudy levels.
Nutrient intake was measured from four 3-day food records.
Repeated measures analysis of variance, with specific time point changes assessed from paired t tests adjusted for multiple comparisons.
Body mass decreased by a mean +/- SD of 6.7 +/- 3.2 kg at week 12 and 7.8 +/- 6.2 kg by week 32. Walking distance increased by an average of 17.2 +/- 10.0 km/week during the first 12 weeks, and 12.4 +/- 12.4 km/week during the last 20 weeks. Despite a 23% to 36% reduction in energy intake during the study, intake of most nutrients was maintained. Intake of vitamin E, calcium, iron, and zinc decreased significantly from prestudy levels during the first 16 weeks of the intervention, but not at week 32.
Intake of most nutrients can remain at recommended levels when overweight and obese women follow the American Diabetes Association/American Dietetic Association food exchange system during a community-based weight-loss program.