Prevention of overweight and obesity in children and youth: a systematic review and meta-analysis

Abstract

Background: One-third of Canadian children are overweight or obese. This problem carries considerable concern for negative impacts on current and future health. Promoting healthy growth and development is critical. This review synthesized evidence on the effectiveness of behavioural interventions for preventing overweight and obesity in children and adolescents.

Methods: We updated the search of a previous Cochrane review. Five databases were searched up to August 2013. Randomized trials of primary care-relevant behavioural (diet, exercise and lifestyle) interventions for preventing overweight and obesity in healthy normal- or mixed-weight children or youth aged 0-18 years were included if 12-week postbaseline data were provided for body mass index (BMI), BMI z-score, or prevalence of overweight or obesity. Any study reporting harms was included. Meta-analyses were performed if possible. Features of interventions showing significant benefits were examined.

Results: Ninety studies were included, all with mixed-weight populations. Compared with controls, interventions showed a small but significant effect on BMI and BMI z-score (standardized mean difference -0.07, 95% confidence interval [CI] -0.10 to -0.03, I (2) = 74%), a reduction in BMI (mean difference -0.09 kg/m(2), 95% CI -0.16 to -0.03, I (2) = 76%) and a reduced prevalence of overweight and obesity (risk ratio [RR]; RRintervention - RRcontrol 0.94, 95% CI 0.89 to 0.99, I (2) = 0%; number needed to treat 51, 95% CI 29 to 289). Little evidence was available on harms. There was variability across efficacious interventions, although many of the interventions were short-term, involved school-aged children and were delivered in educational settings.

Interpretation: Behavioural prevention interventions are associated with small improvements in weight outcomes in mixed-weight populations of children and adolescents. No intervention strategy consistently produced benefits.

Registration: PROSPERO no. CRD42012002754.

Keywords: This article has been peer reviewed..

Figure 1:

Selection of studies evaluating interventions to prevent overweight and obesity in children and youth. RCT = randomized controlled trial.

Figure 2:

Aggregated risk-of-bias assessment of included studies. Summary data from each study are available in Appendix 2 (www.cmajopen.ca/content/3/1/E23/suppl/DC1).

Figure 4:

Effect of prevention interventions on change in prevalence of overweight or obesity. Values less than 1 indicate a change in prevalence of overweight or obesity in favour of the intervention. 1 = intervention arm 1; 2 = intervention arm 2; F = female; M = male; ob = obese, ow = overweight (overweight and obese are not combined in either extension); RR = risk ratio.

Figure 3A:

(See Figure 3B for part 2). Effect of prevention interventions on change in body mass index (BMI) and BMI z-score. Values less than 0 indicate a change in BMI in favour of the intervention. 1 = intervention arm 1; 2 = intervention arm 2; CI = confidence interval; F = female; M = male; SD = standard deviation; SMD = standardized mean difference; z = BMI z-score.

Figure 3B:

Effect of prevention interventions on change in body mass index (BMI) and BMI z-score. Values less than 0 indicate a change in BMI in favour of the intervention. 1 = intervention arm 1; 2 = intervention arm 2; CI = confidence interval; F = female; M = male; SD = standard deviation; SMD = standardized mean difference; z = BMI z-score.