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.

Keywords: behavior therapy; diet; home food environment; meal replacements; nutritional intervention; nutritional treatment; obesity; treatment; weight loss.

© 2018 American Society for Nutrition. All rights reserved.

Figures

FIGURE 1

Estimated percentage of weight loss over time for the 3 treatment groups with the use of multilevel models. All 3 groups showed significant weight loss over 12 mo that was gradually regained to the 36-mo follow-up. Participants in the HFE group (n = 81) experienced greater weight loss over the course of the study than did participants in the BT group (n = 90) (interaction between 1/time and condition: b = 8.21, SE = 3.14, P = 0.009; interaction between 1/time2 and condition, b = −8.2, SE = 3.27, P = 0.012). BT, behavior therapy; BT+MR, behavior therapy plus meal replacements; HFE, home food environment.

FIGURE 2

Estimated change in cognitive restraint scores over time for the 3 treatment groups with the use of multilevel models. The HFE group (n = 81) showed a larger sustained increase in cognitive restraint than the BT (n = 90) and BT+MR (n = 91) groups. In addition, participants in the HFE group were estimated to have 89% more weight loss on average than participants in the BT group as a result of the positive effect of the HFE condition on the percentage of increase in cognitive restraint (unstandardized coefficient = 0.89; 95% CI: 0.2, 2.1). The combined group means ± SDs for the 0-, 6-, 12-, 18-, 24-, and 36-mo visits were 11.57 ± 2.48, 14.20 ± 2.73, 14.00 ± 2.73, 13.52 ± 2.73, 13.10 ± 2.78, and 13.00 ± 3.02, respectively. BT, behavior therapy; BT+MR, behavior therapy plus meal replacements; HFE, home food environment.