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Meta-Analysis
. 2015 Mar 20;10(3):e0121993.
doi: 10.1371/journal.pone.0121993. eCollection 2015.

Intentional weight loss and all-cause mortality: a meta-analysis of randomized clinical trials

Stephen B Kritchevsky  1 , Kristen M Beavers  2 , Michael E Miller  3 , M Kyla Shea  4 , Denise K Houston  1 , Dalane W Kitzman  1 , Barbara J Nicklas  1
Affiliations
Meta-Analysis

Intentional weight loss and all-cause mortality: a meta-analysis of randomized clinical trials

Stephen B Kritchevsky et al. PLoS One. .

Abstract

Background: 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.

Methods: 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.

Results: 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).

Conclusions: In obese adults, intentional weight loss may be associated with approximately a 15% reduction in all-cause mortality.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Study Selection Flowchart.
Flowchart for the selection of eligible studies.
Fig 2
Fig 2. Funnel Plot.
Funnel plot of the point estimate and 95% confidence interval of 12 randomized clinical trials of intentional weight loss.
Fig 3
Fig 3. Forest Plot.
Forest plot showing individual and pooled relative risks of all-cause mortality with 95% confidence intervals across 12 randomized clinical trials of weight loss interventions. Three trials did not report deaths in one intervention arm and are not included in this figure.
See this image and copyright information in PMC

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