Intentional Weight Loss and All-Cause Mortality: A Meta-Analysis of Randomized Clinical Trials

• Published in: PloS one Vol. 10; no. 3; p. e0121993
• Main Authors: Kritchevsky, Stephen B., Beavers, Kristen M., Miller, Michael E., Shea, M. Kyla, Houston, Denise K., Kitzman, Dalane W., Nicklas, Barbara J.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 20.03.2015; Public Library of Science (PLoS)
• Subjects: Adults; Age; Blood pressure; Body mass; Body mass index; Body weight loss; Cardiology; Clinical trials; Confidence intervals; Data processing; Diabetes; Exercise; Fatalities; Female; Follow-Up Studies; Health aspects; Health risks; Heterogeneity; Humans; Identification methods; Internal medicine; Intervention; Male; Medical research; Medicine; Meta-analysis; Middle Aged; Mortality; Mortality risk; Nutrition research; Obesity; Observational studies; Older people; Physical fitness; Publication Bias; Randomization; Randomized Controlled Trials as Topic; Risk analysis; Risk factors; Sensitivity analysis; Studies; Systematic review; Task forces; Weight control; Weight Loss; Weight reduction; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0121993

Obesity is associated with increased mortality, and weight loss trials show rapid improvement in many mortality risk factors. Yet, observational studies typically associate weight loss with higher mortality risk. The purpose of this meta-analysis of randomized controlled trials (RCTs) of weight loss was to clarify the effects of intentional weight loss on mortality. 2,484 abstracts were identified and reviewed in PUBMED, yielding 15 RCTs reporting (1) randomization to weight loss or non-weight loss arms, (2) duration of ≥18 months, and (3) deaths by intervention arm. Weight loss interventions were all lifestyle-based. Relative risks (RR) and 95% confidence intervals (95% CI) were estimated for each trial. For trials reporting at least one death (n = 12), a summary estimate was calculated using the Mantel-Haenszel method. Sensitivity analysis using sparse data methods included remaining trials. Trials enrolled 17,186 participants (53% female, mean age at randomization = 52 years). Mean body mass indices ranged from 30-46 kg/m2, follow-up times ranged from 18 months to 12.6 years (mean: 27 months), and average weight loss in reported trials was 5.5±4.0 kg. A total of 264 deaths were reported in weight loss groups and 310 in non-weight loss groups. The weight loss groups experienced a 15% lower all-cause mortality risk (RR = 0.85; 95% CI: 0.73-1.00). There was no evidence for heterogeneity of effect (Cochran's Q = 5.59 (11 d.f.; p = 0.90); I2 = 0). Results were similar in trials with a mean age at randomization ≥55 years (RR = 0.84; 95% CI 0.71-0.99) and a follow-up time of ≥4 years (RR = 0.85; 95% CI 0.72-1.00). In obese adults, intentional weight loss may be associated with approximately a 15% reduction in all-cause mortality.