Effects of weight loss interventions for adults who are obese on mortality, cardiovascular disease and cancer

a systematic review and meta-analysis

Chenhan Ma, Alison Avenell, Mark Bolland, Jemma Hudson, Fiona Stewart, Clare Robertson, Pawana Sharma, Cynthia Fraser, Graeme MacLennan

Research output: Contribution to journalArticle

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Abstract

Objective
To assess if weight loss interventions for adults with obesity affect all-cause, cardiovascular and cancer mortality, cardiovascular disease, cancer, and body weight.

Design
Systematic review and meta-analysis of randomised controlled trials (RCTs) using random effects, estimating risk ratios (RRs) and mean differences (MDs). Heterogeneity investigated using Cochran’s Q and I2 statistics. Quality of evidence assessed by GRADE criteria.

Data sources
We searched Medline, Embase, the Cochrane Central Register of Controlled Trials, and full texts in our trials’ registry for data not evident in databases. We contacted authors for unpublished data.

Eligibility criteria for selecting studies
RCTs of dietary interventions targeting weight loss, with or without exercise advice or programmes, for adults with obesity and follow-up ≥ 1 year.

Results
We included 54 RCTs with 30,206 participants. All but one trial evaluated low-fat reducing diets. For the primary outcome, there was high quality evidence that weight loss interventions decrease all-cause mortality (34 trials, 685 events; RR 0.82, 95% CI (Confidence Interval): 0.71 to 0.95), 6 fewer deaths per 1000 participants (95% CI 2 fewer to 10 fewer). For other primary outcomes there was moderate quality evidence for an effect on cardiovascular mortality (8 trials, 134 events; RR 0.93, 95% CI: 0.67 to 1.31) and very low quality evidence for an effect on cancer mortality (8 trials, 34 events; RR 0.58, 95% CI 0.30 to 1.11).

Twenty four trials (15,176 participants) reported high quality evidence on participants developing new cardiovascular events (1043 events; RR 0.93, 95% CI 0.83 to 1.04).

Nineteen trials (6330 participants) provided very low quality evidence on participants developing new cancers (103 events; RR 0.92, 95% CI 0.63 to 1.36).

Conclusions
Weight reducing diets, usually low in fat and saturated fat, with or without exercise advice or programmes, may reduce premature all-cause mortality in adults with obesity.
Original languageEnglish
Article numberj4849
JournalBMJ
Volume359
DOIs
Publication statusPublished - 14 Nov 2017

Fingerprint

Meta-Analysis
Weight Loss
Cardiovascular Diseases
Odds Ratio
Confidence Intervals
Mortality
Reducing Diet
Neoplasms
Randomized Controlled Trials
Obesity
Fats
Fat-Restricted Diet
Registries
Body Weight
Databases

Keywords

  • obesity
  • weight reduction
  • reducing diet
  • mortality
  • cardiovascular disease
  • cancer
  • systematic review
  • randomised controlled trials

Cite this

Effects of weight loss interventions for adults who are obese on mortality, cardiovascular disease and cancer : a systematic review and meta-analysis. / Ma, Chenhan; Avenell, Alison; Bolland, Mark; Hudson, Jemma; Stewart, Fiona; Robertson, Clare; Sharma, Pawana; Fraser, Cynthia; MacLennan, Graeme.

In: BMJ, Vol. 359, j4849, 14.11.2017.

Research output: Contribution to journalArticle

@article{d1d50143e1a9454386a27cc867fa9c20,
title = "Effects of weight loss interventions for adults who are obese on mortality, cardiovascular disease and cancer: a systematic review and meta-analysis",
abstract = "ObjectiveTo assess if weight loss interventions for adults with obesity affect all-cause, cardiovascular and cancer mortality, cardiovascular disease, cancer, and body weight.DesignSystematic review and meta-analysis of randomised controlled trials (RCTs) using random effects, estimating risk ratios (RRs) and mean differences (MDs). Heterogeneity investigated using Cochran’s Q and I2 statistics. Quality of evidence assessed by GRADE criteria.Data sourcesWe searched Medline, Embase, the Cochrane Central Register of Controlled Trials, and full texts in our trials’ registry for data not evident in databases. We contacted authors for unpublished data. Eligibility criteria for selecting studies RCTs of dietary interventions targeting weight loss, with or without exercise advice or programmes, for adults with obesity and follow-up ≥ 1 year.ResultsWe included 54 RCTs with 30,206 participants. All but one trial evaluated low-fat reducing diets. For the primary outcome, there was high quality evidence that weight loss interventions decrease all-cause mortality (34 trials, 685 events; RR 0.82, 95{\%} CI (Confidence Interval): 0.71 to 0.95), 6 fewer deaths per 1000 participants (95{\%} CI 2 fewer to 10 fewer). For other primary outcomes there was moderate quality evidence for an effect on cardiovascular mortality (8 trials, 134 events; RR 0.93, 95{\%} CI: 0.67 to 1.31) and very low quality evidence for an effect on cancer mortality (8 trials, 34 events; RR 0.58, 95{\%} CI 0.30 to 1.11).Twenty four trials (15,176 participants) reported high quality evidence on participants developing new cardiovascular events (1043 events; RR 0.93, 95{\%} CI 0.83 to 1.04).Nineteen trials (6330 participants) provided very low quality evidence on participants developing new cancers (103 events; RR 0.92, 95{\%} CI 0.63 to 1.36).ConclusionsWeight reducing diets, usually low in fat and saturated fat, with or without exercise advice or programmes, may reduce premature all-cause mortality in adults with obesity.",
keywords = "obesity, weight reduction, reducing diet, mortality, cardiovascular disease, cancer, systematic review, randomised controlled trials",
author = "Chenhan Ma and Alison Avenell and Mark Bolland and Jemma Hudson and Fiona Stewart and Clare Robertson and Pawana Sharma and Cynthia Fraser and Graeme MacLennan",
note = "We thank Associate Professor Andrew Grey for helping to resolve discrepancies in data extraction and interpretation for cardiovascular events and cancer events. We thank trialists from 16 studies for clarifying or providing additional information for this review [Andrews 2011, Aveyard 2016, Bennett 2012, de Vos 2014, Finnish Diabetes Prevention Study 2009, Goodwin 2014, Green 2015, Horie 2016, Hunt (FFIT) 2014, Katula 2013, Li (Da Qing) 2014, Logue 2005, Ma 2013, O’Neil 2016, Rejeski (CLIP) 2011, Uusitupa 1993] and also others who provided information, but their trials were later found not to fulfil our inclusion criteria. Funding: The Health Services Research Unit is funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorate.",
year = "2017",
month = "11",
day = "14",
doi = "10.1136/bmj.j4849",
language = "English",
volume = "359",
journal = "BMJ",
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T1 - Effects of weight loss interventions for adults who are obese on mortality, cardiovascular disease and cancer

T2 - a systematic review and meta-analysis

AU - Ma, Chenhan

AU - Avenell, Alison

AU - Bolland, Mark

AU - Hudson, Jemma

AU - Stewart, Fiona

AU - Robertson, Clare

AU - Sharma, Pawana

AU - Fraser, Cynthia

AU - MacLennan, Graeme

N1 - We thank Associate Professor Andrew Grey for helping to resolve discrepancies in data extraction and interpretation for cardiovascular events and cancer events. We thank trialists from 16 studies for clarifying or providing additional information for this review [Andrews 2011, Aveyard 2016, Bennett 2012, de Vos 2014, Finnish Diabetes Prevention Study 2009, Goodwin 2014, Green 2015, Horie 2016, Hunt (FFIT) 2014, Katula 2013, Li (Da Qing) 2014, Logue 2005, Ma 2013, O’Neil 2016, Rejeski (CLIP) 2011, Uusitupa 1993] and also others who provided information, but their trials were later found not to fulfil our inclusion criteria. Funding: The Health Services Research Unit is funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorate.

PY - 2017/11/14

Y1 - 2017/11/14

N2 - ObjectiveTo assess if weight loss interventions for adults with obesity affect all-cause, cardiovascular and cancer mortality, cardiovascular disease, cancer, and body weight.DesignSystematic review and meta-analysis of randomised controlled trials (RCTs) using random effects, estimating risk ratios (RRs) and mean differences (MDs). Heterogeneity investigated using Cochran’s Q and I2 statistics. Quality of evidence assessed by GRADE criteria.Data sourcesWe searched Medline, Embase, the Cochrane Central Register of Controlled Trials, and full texts in our trials’ registry for data not evident in databases. We contacted authors for unpublished data. Eligibility criteria for selecting studies RCTs of dietary interventions targeting weight loss, with or without exercise advice or programmes, for adults with obesity and follow-up ≥ 1 year.ResultsWe included 54 RCTs with 30,206 participants. All but one trial evaluated low-fat reducing diets. For the primary outcome, there was high quality evidence that weight loss interventions decrease all-cause mortality (34 trials, 685 events; RR 0.82, 95% CI (Confidence Interval): 0.71 to 0.95), 6 fewer deaths per 1000 participants (95% CI 2 fewer to 10 fewer). For other primary outcomes there was moderate quality evidence for an effect on cardiovascular mortality (8 trials, 134 events; RR 0.93, 95% CI: 0.67 to 1.31) and very low quality evidence for an effect on cancer mortality (8 trials, 34 events; RR 0.58, 95% CI 0.30 to 1.11).Twenty four trials (15,176 participants) reported high quality evidence on participants developing new cardiovascular events (1043 events; RR 0.93, 95% CI 0.83 to 1.04).Nineteen trials (6330 participants) provided very low quality evidence on participants developing new cancers (103 events; RR 0.92, 95% CI 0.63 to 1.36).ConclusionsWeight reducing diets, usually low in fat and saturated fat, with or without exercise advice or programmes, may reduce premature all-cause mortality in adults with obesity.

AB - ObjectiveTo assess if weight loss interventions for adults with obesity affect all-cause, cardiovascular and cancer mortality, cardiovascular disease, cancer, and body weight.DesignSystematic review and meta-analysis of randomised controlled trials (RCTs) using random effects, estimating risk ratios (RRs) and mean differences (MDs). Heterogeneity investigated using Cochran’s Q and I2 statistics. Quality of evidence assessed by GRADE criteria.Data sourcesWe searched Medline, Embase, the Cochrane Central Register of Controlled Trials, and full texts in our trials’ registry for data not evident in databases. We contacted authors for unpublished data. Eligibility criteria for selecting studies RCTs of dietary interventions targeting weight loss, with or without exercise advice or programmes, for adults with obesity and follow-up ≥ 1 year.ResultsWe included 54 RCTs with 30,206 participants. All but one trial evaluated low-fat reducing diets. For the primary outcome, there was high quality evidence that weight loss interventions decrease all-cause mortality (34 trials, 685 events; RR 0.82, 95% CI (Confidence Interval): 0.71 to 0.95), 6 fewer deaths per 1000 participants (95% CI 2 fewer to 10 fewer). For other primary outcomes there was moderate quality evidence for an effect on cardiovascular mortality (8 trials, 134 events; RR 0.93, 95% CI: 0.67 to 1.31) and very low quality evidence for an effect on cancer mortality (8 trials, 34 events; RR 0.58, 95% CI 0.30 to 1.11).Twenty four trials (15,176 participants) reported high quality evidence on participants developing new cardiovascular events (1043 events; RR 0.93, 95% CI 0.83 to 1.04).Nineteen trials (6330 participants) provided very low quality evidence on participants developing new cancers (103 events; RR 0.92, 95% CI 0.63 to 1.36).ConclusionsWeight reducing diets, usually low in fat and saturated fat, with or without exercise advice or programmes, may reduce premature all-cause mortality in adults with obesity.

KW - obesity

KW - weight reduction

KW - reducing diet

KW - mortality

KW - cardiovascular disease

KW - cancer

KW - systematic review

KW - randomised controlled trials

U2 - 10.1136/bmj.j4849

DO - 10.1136/bmj.j4849

M3 - Article

VL - 359

JO - BMJ

JF - BMJ

SN - 0959-8146

M1 - j4849

ER -