Search

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.

Background: Once weight loss is achieved, the challenge is to maintain this benefit. This review reports on the effectiveness of programs for weight-loss maintenance, as part of a larger review examining treatments for overweight and obese adults., Methods: We updated the search of a 2011 review on screening and management of overweight and obese adults. Four databases were searched. For inclusion, participants had to have lost weight in treatment and then been randomly assigned to a weight-maintenance intervention or control conditions. Studies from the 2011 review that met the criteria were included. Data were extracted and pooled (where possible) for outcomes related to weight-loss maintenance., Results: Eight studies were included. Compared with control participants, intervention participants regained less weight (mean difference [MD] -1.44 kg, 95% confidence interval [CI] -2.42 to -0.47), regardless of whether the intervention was behavioural (MD-1.56 kg, 95% CI -3.10 to -0.02) or pharmacologic plus behavioural (MD -1.39 kg, 95% CI -2.86 to 0.08). Intervention participants also showed better weight maintenance than the control participants in terms of waist circumference (MD -2.30 cm, 95% CI -3.45 to -1.15) and body mass index (MD -0.95 kg/m(2), 95% CI -1.67 to -0.23). Participants undergoing pharmacologic plus behavioural interventions were more likely to maintain a loss of 5% or more of initial body weight than those in the control group (risk ratio [RR] 1.33, 95% CI 1.15 to 1.54); no difference was found for maintaining a weight loss of 10% or more (RR 1.76, 95% CI 0.75 to 4.12)., Interpretation: Moderate quality evidence shows that overweight and obese adults can benefit from interventions for weight maintenance following weight loss. However, there is insufficient evidence on the long-term sustainability of these benefits., Registration: PROSPERO no. CRD42012002753.

Background: Obesity is a major public health issue. This review updates the evidence on the effectiveness of behavioural and pharmacologic treatments for overweight and obesity in adults., Methods: We updated the search conducted in a previous review. Randomized trials of primary-care-relevant behavioural (diet, exercise and lifestyle) and pharmacologic (orlistat and metformin) with or without behavioural treatments in overweight and obese adults were included if 12-month, postbaseline data were provided for weight outcomes. Studies reporting harms were included regardless of design. Data were extracted and pooled wherever possible for 5 weight outcomes, 6 secondary health outcomes and 4 adverse events categories., Results: We identified 68 studies, most consisted of short-term (≤ 12 mo) treatments using diet (n = 8), exercise (n = 4), diet and exercise (n = 10), lifestyle (n = 19), orlistat (n = 25) or metformin (n = 4). Compared with the control groups, intervention participants had a greater weight loss of -3.02 kg (95% confidence interval [CI] -3.52 to -2.52), a greater reduction in waist circumference of -2.78 cm (95% CI -3.34 to -2.22) and a greater reduction in body mass index of -1.11 kg/m(2) (95% CI -1.39 to -0.84). The relative risk for loss of ≥ 5% body weight was 1.77 (95% CI 1.58-1.99, [number needed to treat 5, 95% CI 4-7]), and the relative risk for loss of ≥ 10% body weight was 1.91 (95% CI 1.69-2.16, [number needed to treat 9, 95% CI 7-12]). Incidence of type 2 diabetes was lower among pre-diabetic intervention participants (relative risk 0.62 [95% CI 0.50-0.77], number needed to treat 17 [95% CI 13-29]). With prevalence rates for type 2 diabetes on the rise, weight loss coupled with a reduction in the incidence of type 2 diabetes could potentially have a significant benefit on population health and a possible reduction in need for drug treatments for glycemic control., Interpretation: There is moderate quality evidence that behavioural and pharmacologic plus behvioural, treatments for overweight and obesity in adults lead to clinically important reductions in weight and incidence of type 2 diabetes in pre-diabetic populations., Registration: PROSPERO no. CRD42012002753.

Background: The prevalence of normal-weight adults is decreasing, and the proportion in excessive weight categories (body mass index ≥ 25) is increasing. In this review, we sought to identify interventions to prevent weight gain in normal-weight adults., Methods: We searched multiple databases from January 1980 to June 2013. We included randomized trials of primary care-relevant behavioural, complementary or alternative interventions for preventing weight gain in normal-weight adults that reported weight change at least 12 months after baseline. We included any studies reporting harms. We planned to extract and pool data for 4 weight outcomes, 6 secondary health outcomes and 5 adverse events categories., Results: One small study provided moderate-quality evidence. The 12-month program, which used education and financial strategies and was offered more than 25 years ago in the United States, was successful in stabilizing weight and producing weight loss. More intervention participants maintained their baseline weight or lost weight than controls (82% v. 56%, p < 0.0001), and program participants maintained their weight better than controls by showing greater weight reduction by the end of the intervention (mean difference adjusted for height -0.82, 95% confidence interval -1.57 to -0.06, kg). No evidence was available for sustained effects or for any other weight outcomes, secondary outcomes or harms., Interpretation: We were unable to determine whether behavioural interventions led to weight-gain prevention and improved health outcomes in normal-weight adults. Given the importance of primary prevention, and the difficulty of losing weight and maintaining weight loss, this paucity of evidence is surprising and leaves clinicians and public health practitioners with unclear direction., Registration: PROSPERO no. CRD42012002753.