Effects of anti-obesity drugs, diet, and exercise on weight-loss maintenance after a very-low-calorie diet or low-calorie diet: a systematic review and meta-analysis of randomized controlled trials

Abstract

Background: Weight-loss maintenance remains a major challenge in obesity treatment.

Objective: The objective was to evaluate the effects of anti-obesity drugs, diet, or exercise on weight-loss maintenance after an initial very-low-calorie diet (VLCD)/low-calorie diet (LCD) period (<1000 kcal/d).

Design: We conducted a systematic review by using MEDLINE, the Cochrane Controlled Trial Register, and EMBASE from January 1981 to February 2013. We included randomized controlled trials that evaluated weight-loss maintenance strategies after a VLCD/LCD period. Two authors performed independent data extraction by using a predefined data template. All pooled analyses were based on random-effects models.

Results: Twenty studies with a total of 27 intervention arms and 3017 participants were included with the following treatment categories: anti-obesity drugs (3 arms; n = 658), meal replacements (4 arms; n = 322), high-protein diets (6 arms; n = 865), dietary supplements (6 arms; n = 261), other diets (3 arms; n = 564), and exercise (5 arms; n = 347). During the VLCD/LCD period, the pooled mean weight change was -12.3 kg (median duration: 8 wk; range 3-16 wk). Compared with controls, anti-obesity drugs improved weight-loss maintenance by 3.5 kg [95% CI: 1.5, 5.5 kg; median duration: 18 mo (12-36 mo)], meal replacements by 3.9 kg [95% CI: 2.8, 5.0 kg; median duration: 12 mo (10-26 mo)], and high-protein diets by 1.5 kg [95% CI: 0.8, 2.1 kg; median duration: 5 mo (3-12 mo)]. Exercise [0.8 kg; 95% CI: -1.2, 2.8 kg; median duration: 10 mo (6-12 mo)] and dietary supplements [0.0 kg; 95% CI: -1.4, 1.4 kg; median duration: 3 mo (3-14 mo)] did not significantly improve weight-loss maintenance compared with control.

Conclusion: Anti-obesity drugs, meal replacements, and high-protein diets were associated with improved weight-loss maintenance after a VLCD/LCD period, whereas no significant improvements were seen for dietary supplements and exercise.

FIGURE 1.

Flowchart of included studies. RCT, randomized controlled trial.

FIGURE 2.

Overview of body weight changes in the included randomized controlled trials (n = 20) that evaluated different anti-obesity drugs, diet, and exercise weight-loss maintenance strategies after an initial very-low-calorie diet or low-calorie diet (<1000 kcal/d). CLA, conjugated linoleic acid; GI, glycemic index.

FIGURE 3.

Overview of changes in body weight during the rapid weight-loss phase and the weight-loss maintenance period in 20 randomized controlled trials that evaluated different anti-obesity drug, diet, and exercise weight-loss maintenance strategies after an initial very-low-calorie diet or low-calorie diet (<1000 kcal/d). The gray lines represent the control subjects in each subcategory. Anti-obesity drugs: sibutramine and orlistat. Dietary supplements: green tea, high fiber, oil supplement, and conjugated linoleic acid. Other macronutrients: low fat, low glycemic index, and Healthy Eating Pyramid. The random-effects model was used to weight and pool the studies within each treatment arm (intervention and control) after the very-low-calorie diet or low-calorie diet period and maintenance period. The mean increase for each month was estimated from these 2 measurements. Weighted mean differences between the intervention and control groups at follow-up were estimated by using a random-effects model.

FIGURE 4.

Forest plot of control group subtracted weight change (kg) at the end of a weight-loss maintenance program, after an initial very-low-calorie diet or low-calorie diet (<1000 kcal/d), in 20 randomized controlled trials. Data are weighted mean differences from a random-effects model. Error bars depict 95% CIs. The I² statistic refers to heterogeneity. CLA, conjugated linoleic acid; E%, percentage of energy; GI, glycemic index.