Evaluation of meal replacements and a home food environment intervention for long-term weight loss: a randomized controlled trial

Background: Lifestyle change treatments for weight loss produce medically meaningful weight reductions, but lost weight is usually regained. Meal replacements (MRs) represent one avenue for improving long-term weight loss. Another, nutrition-focused approach involves having participants make specific changes in the energy density, composition, and structure of the foods in their personal food environments. Objective: Three conditions were compared: behavior therapy (BT), BT plus MRs (BT+ MR), and a nutrition-focused treatment aimed at modifying the home food environment (HFE). Design: Overweight and obese individuals (n = 262) were randomly assigned to 1 of the 3 conditions. Treatment occurred in weekly groups for 6 mo and in biweekly groups for 6 mo. Assessments were conducted at baseline and at 6, 12, 18, 24, and 36 mo. Multilevel models were used to estimate weight-change trajectories for each participant and to examine the treatment group effect on long-term weight loss. Results: A multilevel analysis indicated that all 3 groups showed significant weight loss over 12 mo that was gradually regained to the 36-mo follow-up. Mean +/- SD percentages of baseline weight loss at 12 mo for BT, BT+ MR, and HFE were 9.41% +/- 7.92%, 10.37% +/- 7.77%, and 10.97% +/- 7.79%, respectively. Comparable percentages at 36 mo were 4.21%+/- 8.64%, 3.06%+/- 6.93%, and 4.49%+/- 7.83%. Those in the HFE condition lost more weight than those receiving BT through the 36-mo assessment (P < 0.01), as reflected in 2 treatment x time interactions. Further analyses showed that HFE produced the largest increases in cognitive restraint and that this increase largely mediated the HFE group's improved weight loss. Conclusion: The nutrition-focused intervention studied here produced modestly greater long-term weight loss than BT, an effect that was largely explainable by an unexpected boost in cognitive restraint in this condition.