Editorial group: Cochrane Methodology Review Group. Publication status and date: New search for studies and content updated (conclusions changed), published in Issue 3, 2021.

Background Adults with severe obesity [body mass index (BMI) of ≥ 35 kg/m2] have an increased risk of comorbidities and psychological, social and economic consequences. Objectives Systematically review bariatric surgery, weight-management programmes (WMPs) and orlistat pharmacotherapy for adults with severe obesity, and evaluate the feasibility, acceptability, clinical effectiveness and cost-effectiveness of treatment. Data sources Electronic databases including MEDLINE, EMBASE, PsycINFO, the Cochrane Central Register of Controlled Trials and the NHS Economic Evaluation Database were searched (last searched in May 2017). Review methods Four systematic reviews evaluated clinical effectiveness, cost-effectiveness and qualitative evidence for adults with a BMI of ≥ 35 kg/m2. Data from meta-analyses populated a microsimulation model predicting costs, outcomes and cost-effectiveness of Roux-en-Y gastric bypass (RYGB) surgery and the most effective lifestyle WMPs over a 30-year time horizon from a NHS perspective, compared with current UK population obesity trends. Interventions were cost-effective if the additional cost of achieving a quality-adjusted life-year is < £20,000–30,000. Results A total of 131 randomised controlled trials (RCTs), 26 UK studies, 33 qualitative studies and 46 cost-effectiveness studies were included. From RCTs, RYGB produced the greatest long-term weight change [–20.23 kg, 95% confidence interval (CI) –23.75 to –16.71 kg, at 60 months]. WMPs with very low-calorie diets (VLCDs) produced the greatest weight loss at 12 months compared with no WMPs. Adding a VLCD to a WMP gave an additional mean weight change of –4.41 kg (95% CI –5.93 to –2.88 kg) at 12 months. The intensive Look AHEAD WMP produced mean long-term weight loss of 6% in people with type 2 diabetes mellitus (at a median of 9.6 years). The microsimulation model found that WMPs were generally cost-effective compared with population obesity trends. Long-term WMP weight regain was very uncertain, apart from Look AHEAD. The addition of a VLCD to a WMP was not cost-effective compared with a WMP alone. RYGB was cost-effective compared with no surgery and WMPs, but the model did not replicate long-term cost savings found in previous studies. Qualitative data suggested that participants could be attracted to take part in WMPs through endorsement by their health-care provider or through perceiving innovative activities, with WMPs being delivered to groups. Features improving long-term weight loss included having group support, additional behavioural support, a physical activity programme to attend, a prescribed calorie diet or a calorie deficit. Limitations Reviewed studies often lacked generalisability to UK settings in terms of participants and resources for implementation, and usually lacked long-term follow-up (particularly for complications for surgery), leading to unrealistic weight regain assumptions. The views of potential and actual users of services were rarely reported to contribute to service design. This study may have failed to identify unpublished UK evaluations. Dual, blinded numerical data extraction was not undertaken. Conclusions Roux-en-Y gastric bypass was costly to deliver, but it was the most cost-effective intervention. Adding a VLCD to a WMP was not cost-effective compared with a WMP alone. Most WMPs were cost-effective compared with current population obesity trends. Future work Improved reporting of WMPs is needed to allow replication, translation and further research. Qualitative research is needed with adults who are potential users of, or who fail to engage with or drop out from, WMPs. RCTs and economic evaluations in UK settings (e.g. Tier 3, commercial programmes or primary care) should evaluate VLCDs with long-term follow-up (≥ 5 years). Decision models should incorporate relevant costs, disease states and evidence-based weight regain assumptions. Study registration This study is registered as PROSPERO CRD42016040190. Funding The National Institute for Health Research Health Technology Assessment programme. The Health Services Research Unit and Health Economics Research Unit are core funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorate.

A school-based, peer-led, SM intervention developed by adolescents attending high schools in low-income neighborhoods effectively improved the healthy choices of their school-aged peers, leading to increased fruit consumption and PA in adolescents of both genders. Furthermore, adolescent males were more sensitive to improvements in healthy choices, showing increased vegetable consumption and decreased sedentary behavior.

BackgroundMexico is a developing country with one of the highest youth obesity rates worldwide; >34% of children and adolescents between 5 and 19 years of age are overweight or obese.ObjectivesThe current review seeks to compile, describe, and analyze dietary conditions, physical activity, socioeconomic status, and cultural factors that create and exacerbate an obesogenic environment among Mexican youth.DesignA narrative review was performed using PubMed and the Cochrane Library databases, as well as grey literature data from the Mexican government, academics, and statistical reports from nongovernmental organizations, included in electronic formats.ResultsThe recent socioeconomic and nutritional transition has resulted in reduced healthy meal options at public schools, high rates of sedentary lifestyles among adolescents, lack of open spaces and playgrounds, socioeconomic deprivation, false or misunderstood sociocultural traditional beliefs, misconceptions about health, a high percentage of overweight or obese adults, and low rates of maternal breastfeeding. Some of the factors identified are exacerbating the obesity problem in this population. Current evidence also shows that more policies and health programs are needed for prevention of childhood and adolescent obesity. Mexico presents alarming obesity levels, which need to be curtailed and urgently reversed.ConclusionsThe present narrative review presents an overview of dietary, physical activity, societal and cultural preconceptions that are potentially modifiable obesity-promoting factors in Mexican youth. Measures to control these factors need to be implemented in all similar developing countries by governments, policy makers, stakeholders, and health care professionals to tackle obesity in children and young people.

BackgroundAn important challenge of school-based childhood obesity (OB) intervention programs is understanding the maintenance of the effects after cessation of the intervention to overcome the limitations of follow-up studies. The aim of this study is to verify the sustainability of the benefits achieved at a 4-year follow-up of the post-Educació en Alimentació (EDAl) program intervention cessation by assessing the OB-related outcomes and lifestyles of 13- to 15-year-old adolescents.MethodsThis paper describes a 4-year follow-up study after the cessation of a school-based randomized controlled intervention in adolescents (n = 349, intervention; n = 154, control) with baseline and 4-year follow-up data from high schools in Reus (intervention group), Salou, Cambrils and Vila-seca (control group). The outcomes are body mass index (BMI), BMI z-score, and OB prevalence according to the World Health Organization and International Obesity Task Force criteria and lifestyle data (obtained from questionnaires).ResultsCompared with the control girls, the intervention girls showed reduced BMI z-scores (−0.33 units, p < 0.01) from baseline (2007) to the 4-year follow-up post-intervention (2014). Compared with the control boys, the intervention boys showed reduced OB prevalence (−7.7%; p = 0.02). Compared with the control boys, more boys in the intervention group (19% increase; p = 0.059) showed ≥4 h/week after-school physical activity (PA). A decrease in the consumption of dairy products, fruits and fish was observed in both groups.ConclusionsAt the 4-year post-intervention follow-up of the EdAl program, compared with the control groups, girls had lower BMI z-scores and boys had lower OB prevalence from the intervention. The encouragement in after-school PA was long-lasting and maintained after the cessation of the intervention, whereas healthy food habits must be further reinforced in adolescents.Trial registrationISRCTN29247645.Electronic supplementary materialThe online version of this article (10.1186/s12889-017-5006-0) contains supplementary material, which is available to authorized users.