Weight-loss outcomes: a systematic review and meta-analysis of weight-loss clinical trials with a minimum 1-year follow-up.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized clinical trials
PubMed 17904936 · doi:10.1016/j.jada.2007.07.017
What was done
A systematic review and meta-analysis of randomized clinical trials with at least 1 year of follow-up evaluated weight-loss interventions in individuals with overweight or obesity. Eighty studies were identified. Interventions were classified into eight categories: diet alone, diet and exercise, exercise alone, meal replacements, very-low-energy diets, weight-loss medications (orlistat and sibutramine), and advice alone. Outcomes were weight loss at 6, 12, 24, 36, and 48 months, evaluated through pooled means and meta-analysis of effect sizes using Hedges' gu.
What was found
Interventions using reduced-energy diets and/or weight-loss medications achieved a mean weight loss of 5 to 8.5 kg (5% to 9%) during the first 6 months, with weight loss plateauing around 6 months. In trials followed up to 48 months, an average weight loss of 3 to 6 kg (3% to 6%) was maintained, with no groups regaining weight back to baseline. In contrast, advice-only and exercise-alone interventions resulted in minimal weight loss at all time points.
Why it matters
This study establishes realistic long-term trajectories for major weight-loss strategies, demonstrating that diet-based interventions can maintain modest weight loss for up to four years, whereas exercise or advice alone yields minimal reduction.
Limits
The abstract reports pooled averages and percentage ranges but does not provide total participant count, exact effect sizes, confidence intervals, or measures of between-study heterogeneity. Adherence, adverse events, and dropout rates are not reported in the abstract.