Relationship between changes in food group variety, dietary intake, and weight during obesity treatment

Background: Experimental studies show diets with greater variety in energy-dense foods increase consumption and body weight. Reducing variety in energy-dense food groups may decrease energy and dietary fat intake, promoting weight loss. Objective: This study examined changes in food group variety during obesity treatment and the relation between changes in food group variety, dietary intake, and weight. Design: Overweight men and women (n=202) were randomly assigned to one of two standard behavioral treatments with varying exercise prescriptions (exercise level of 4186 kJ/week (1000 kcal/week) or 10465 kJ/week (2500 kcal/week)), but received the same diet. Complete measures were obtained from 122 participants, of which 70 (58%) were female, with a mean body mass index of 31.3 kg/m(2) (s.d.=2.5). Measurements: Food group variety and diet composition were assessed at 0, 6, and 18 months from food-frequency questionnaires. Food group variety was calculated as percent of foods consumed on a weekly basis within a food group, irrespective of servings consumed. Results: Participants reported increased variety (Pless than or equal to0.001) in low-fat breads (LFB) and vegetables, and decreased variety (Pless than or equal to0.001) in high-fat foods (HFF), and fats, oils, and sweets (FOS) over the course of the 18-month study. From 0 to 6 months, decreased HFF and FOS variety was associated with reduced energy and percent dietary fat intake, and decreased HFF variety was related to weight loss. From 6 to 18 months, decreased HFF variety and increased LFB variety was associated with reduced percent dietary fat consumed and weight loss. Conclusion: Changing variety in specific food groups may help in adopting and sustaining a diet low in energy and fat, producing better weight loss and weight loss maintenance.