Key Question 2: Intermediate Outcomes
Medium- to high-intensity dietary interventions (with
or without concomitant physical activity counseling) decreased
body mass index at about 12 months. Statistical
heterogeneity was high (I2 70%), making interpretation
of pooled effect sizes questionable (Table 3). Two thirds of
the trials of high-intensity dietary interventions, however,
reported statistically significant group differences, suggesting
that although the amount of weight change varied
greatly from study to study, these interventions are likely to
reduce weight (decrease in body mass index of approximately
0.3 to 0.7 kg/m2). Physical activity counseling trials
were limited to primarily medium-intensity interventions
for this outcome and generally did not reduce adiposity.
Five trials evaluating high-intensity counseling had
follow-up longer than 12 months; the reduction in body
mass index persisted up to 72 months, although this result
was slightly attenuated (99, 113, 117, 118, 121).