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

ABSTRACT 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 × 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. This study was registered at clinicaltrials.gov as NCT01065974.