title: Intentional weight loss and all-cause mortality: a meta-analysis of randomized clinical trials.
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.
authors: Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, United States of America.
authors: Stephen B
authors: SB
authors: Kritchevsky
authors: Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, United States of America; Department of Health and Exercise Science, Wake Forest University, Winston-Salem, NC, United States of America.
authors: Kristen M
authors: KM
authors: Beavers
authors: Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, United States of America; Department of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, NC, United States of America.
authors: Michael E
authors: ME
authors: Miller
authors: Human Nutrition Research Center on Aging, Tufts University, Boston, MA, United States of America.
authors: M Kyla
authors: MK
authors: Shea
authors: Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, United States of America.
authors: Denise K
authors: DK
authors: Houston
authors: Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, United States of America.
authors: Dalane W
authors: DW
authors: Kitzman
authors: Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, United States of America.
authors: Barbara J
authors: BJ
authors: Nicklas
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality; D017594:Publication Bias; D016032:Randomized Controlled Trials as Topic; D015431:Weight Loss