A systematic review and meta-analysis 1 included 80 randomized controlled trials focusing on weight loss (follow-up at least 1-year) with a total of 26 455 adult subjects. Eight types of weight-loss interventions were identified: diet alone, diet and exercise, exercise alone, meal replacements, very-low-energy diets, weight-loss medications (orlistat and sibutramine), and advice alone. 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 (pooled mean weight loss at 6 months 0.7 kg for advice only, 2.4 kg for exercise, 4.9 kg for diet, 7.9 kg for diet plus exercise, 8.2 kg for sibutramine, 8.3 kg for orlistat, 8.6 kg for meal replacements, and 17.9 kg for very-low-energy diet). By meta-analysis, reduced-energy diet interventions, with or without exercise programmes, resulted in more weight loss than advice alone. 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.
A systematic review 2 including 493 study groups with more than 16 000 subjects was abstracted in DARE. It was found that exercise programs were least effective in producing body compositional changes. The effect size for weight lost (kg) in obese adults following diet, exercise or diet plus exercise intervention was 5.1 (SE 0.5), 2.1 (SE 0.5), and 5.5 (SE 0.7), respectively. The actual weight lost (kg) through diet, exercise, and diet plus exercise was 10.7 (SE 0.5), 2.9 (SE 0.4), and 11.0 (SE 0.6), respectively. At one-year follow-up, diet plus exercise tended to be the superior programme.
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