RESUMEN

BACKGROUND: Randomized controlled trials (RCTs) widely considered the gold standard for evidence-based healthcare may be limited in their clinical usefulness in lifestyle interventions for adults with overweight, obesity, or metabolic syndrome. OBJECTIVE: In this systematic review of lifestyle intervention RCTs we delineated trial usefulness. METHODS: Following prospective registration in PROSPERO (CRD4202347896), we conducted a comprehensive search across Medline, Scopus, Web of Science, and the Cochrane Library databases, covering the period from inception to December 2023. RCTs involving dietary interventions, with or without physical activity, and with or without behavioural support were included. Two reviewers independently performed study selection and data extraction. Study usefulness was assessed using a multidimensional 14 item questionnaire. Percentage compliance with usefulness items was computed. RESULTS: Of 1175 records, 30 RCTs (12,841 participants) were included. Among these, 13 (43%) RCTs complied with half of the usefulness items and only 3 (10%) complied with two-thirds of the items. For each usefulness item individually: 30 (100%) reported the burden of the problem addressed, 15 (50%) contextualized the trial through a systematic review, 18 (60%) presented an informative trial with clinically meaningful outcomes evaluated at a stated statistical power, 17 (57%) had low risk of bias, 2 (7%) exhibited pragmatic features pertaining to the trial methodologies and outcomes relevant to real-world application.18 (60%) were patient centred with formal patient involvement, none (0%) demonstrated value for money, 17 (57%) were completed according to their feasibility assessment achieving at least 90% of the estimated sample size, and 30 (100%) reported at least one of five transparency or openness features. CONCLUSION: Only one in 10 lifestyle RCTs met two-thirds of the usefulness features. It is imperative to meet these criteria when devising future trials within the field of nutrition to reduce research waste.