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.
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.
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.
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).
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.
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.