Weight-loss outcomes: a systematic review and meta-analysis of weight-loss clinical trials with a minimum 1-year follow-up

J Am Diet Assoc. 2007 Oct;107(10):1755-67. doi: 10.1016/j.jada.2007.07.017.

Abstract

Objective: To assist health professionals who counsel patients with overweight and obesity, a systematic review was undertaken to determine types of weight-loss interventions that contribute to successful outcomes and to define expected weight-loss outcomes from such interventions.

Design: A search was conducted for weight-loss-focused randomized clinical trials with >or=1-year follow-up. Eighty studies were identified and are included in the evidence table.

Outcomes measures: The primary outcomes were a measure of weight loss at 6, 12, 24, 36, and 48 months. Eight types of weight-loss interventions-diet alone, diet and exercise, exercise alone, meal replacements, very-low-energy diets, weight-loss medications (orlistat and sibutramine), and advice alone-were identified. By using simple pooling across studies, subjects mean amount of weight loss at each time point for each intervention was determined.

Statistical analyses performed: Efficacy outcomes were calculated by meta-analysis and provide support for the pooled data. Hedges' gu was combined across studies to obtain an average effect size (and confidence level).

Results: A mean weight loss of 5 to 8.5 kg (5% to 9%) was observed during the first 6 months from interventions involving a reduced-energy diet and/or weight-loss medications with weight plateaus at approximately 6 months. In studies extending to 48 months, a mean 3 to 6 kg (3% to 6%) of weight loss was maintained with none of the groups experiencing weight regain to baseline. In contrast, advice-only and exercise-alone groups experienced minimal weight loss at any time point.

Conclusions: Weight-loss interventions utilizing a reduced-energy diet and exercise are associated with moderate weight loss at 6 months. Although there is some regain of weight, weight loss can be maintained. The addition of weight-loss medications somewhat enhances weight-loss maintenance.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't
  • Review
  • Systematic Review

MeSH terms

  • Adult
  • Anti-Obesity Agents / therapeutic use*
  • Combined Modality Therapy
  • Cyclobutanes / therapeutic use
  • Diet, Reducing*
  • Exercise / physiology*
  • Female
  • Follow-Up Studies
  • Food, Formulated
  • Humans
  • Lactones / therapeutic use
  • Longitudinal Studies
  • Male
  • Obesity / diet therapy
  • Obesity / drug therapy
  • Obesity / therapy*
  • Orlistat
  • Treatment Outcome
  • Weight Loss*

Substances

  • Anti-Obesity Agents
  • Cyclobutanes
  • Lactones
  • Orlistat
  • sibutramine