Effectiveness of dietary, physical activity, and lifestyle interventions on weight and cardiometabolic outcomes in adults with overweight or obesity: an umbrella review of 112 systematic reviews and meta-analyses from 50 countries

Background Overweight and obesity affect an estimated 2.5 billion adults worldwide. Reviews of single treatment modalities are abundant, but clinicians lack one appraised comparison of nutrition therapy, physical activity, and behavioural modification across outcomes and treatment durations. Methods This was an umbrella review and meta-analysis of systematic reviews and meta-analyses of randomized controlled trials in adults aged 18 years or older with overweight or obesity PubMed was searched (2015–2025) with backward and forward citation tracking. Quality was appraised with AMSTAR 2 and certainty of evidence with GRADE. Primary outcomes were mean change in weight and body mass index (BMI) by intervention type and follow-up duration (<3, 3–6, 6–12, and >12 mo.); secondary outcomes were glycaemic, lipid, and blood pressure parameters. Estimates were pooled using random-effects models. Results Of 1,725 records, 112 reviews (424 comparisons; 2,332 unique randomized trials) were included. All intervention types produced significant but modest weight reduction. Combined diet and physical activity yielded the largest weight reduction beyond 12 mo. (mean difference −3.68 kg; 95% CI: −5.47, −1.89; single contributing review), the largest BMI reduction at <3 mo. (−1.22 kg/m 2 ; 95% CI: −2.31, −0.13), and the greatest improvements in fasting glucose and insulin resistance. Pooled fasting glucose and lipid estimates combine effects reported on differing scales and are exploratory and descriptive only, not absolute mg/dL values. Physical activity produced the largest systolic blood pressure reduction (6–12 mo.: −6.10 mm Hg; 95% CI: −8.07, −4.13). Lipid effects were inconsistent, heterogeneity was high (I 2 commonly 70%–99%), and AMSTAR 2 confidence was low or critically low in 69% of reviews. Conclusion Most non-pharmacological approach reduced weight and BMI, and multicomponent programs combining diet, physical activity, and behavioural support gave the greatest cardiometabolic benefit. Because this benefit was partly independent of the weight lost, such programs remain worthwhile for patients who do not reach conventional 5%–10% weight-loss targets. Registration PROSPERO CRD420251245029 ( https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=1245029 )