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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Long-term weight loss after diet and exercise: a systematic review

CC Curioni and PM Lourenco.

Review published: 2005.

CRD summary

The authors of this review claimed to confirm the important role of diet and exercise in short- and long-term weight loss. Although the conclusions appeared self-evident, they did not follow directly from the results presented, which compared diet and exercise to diet alone.

Authors' objectives

To assess the effectiveness of exercise combined with dietary interventions in initial weight loss and maintenance of weight loss among overweight and obese people

Searching

Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and LILACS were searched up to March 2003. Search terms were reported. Reference lists of published reviews and all relevant studies were checked for further studies. No language restrictions were imposed.

Study selection

Randomised controlled trials (RCTs) of diet, exercise or both in overweight or obese adults aged 18 and over were eligible for inclusion in the review. Overweight or obese was defined as having a body mass index (BMI) of greater than 25. Pregnant women were excluded, but no health status restrictions were applied. Diet included any type of calorie restriction. Exercise included any type of exercise where the recommended activity could be quantified. Interventions could be associated with behavioural therapy, but not with use of medication. Eligible trials needed to have a follow-up period of at least one year. Sample size varied from 40 to 127 participants. Ages ranged from 21 to 65 years. Three studies included only women, one included only men and the remaining two had both genders. In all but one study, patients were seen once a week during the entire period of intervention, usually in small groups. Intervention duration ranged from 10 to 52 weeks. Follow-up ranged from 12 to 24 months. All trials were conducted in Finland or USA.

Two authors independently considered studies for inclusion. Disagreements were resolved by consensus.

Assessment of study quality

Study quality was rated with criteria adapted from the Jadad scale and Delphi list.

The authors did not state how many reviewers were involved in the assessment of study quality.

Data extraction

Baseline weight, initial weight loss following the intervention and weight loss after one year follow-up were extracted for each study's treatment groups. Individual study effect size was obtained by comparing reduced weight in the combined diet and exercise intervention group versus the diet alone control group. Data obtained after periods greater than one year were only considered if the one-year results were not described. Only the last publications of trials were included.

The authors did not state how many reviewers were involved in data extraction.

Methods of synthesis

Trials were combined in meta-analyses, weighted by the inverse variance method, using a fixed-effect model. The authors calculated a pooled result for weight loss based on standardised mean differences (SMDs) for the post-intervention period and for maintenance at one-year follow-up. Study heterogeneity was assessed using the Χ2 test. Sensitivity analysis that assessed the influence of studies with methodological flaws was planned.

Results of the review

Six trials were included in the review (n=407). Dropout was less than 20% in all trials except one. No study gave information on blinding or intention-to-treat analysis. Two described the randomisation process.

Post-intervention: Mean weight loss in the diet and exercise groups was 13kg compared to 9.9kg in the the diet-only group, but this result was not statistically significant. Results remained the same when one study with a drop-out rate greater than 20% was removed.

One-year follow-up: Mean weight loss in the diet and exercise groups was 6.7kg compared to 4.5kg in the diet-only groups, but this result was not statistically significant. Removal of the study with over 20% drop-out resulted in a statistically significant difference in favour of diet and exercise (p=0.03).

Authors' conclusions

Diet associated with exercise resulted in significant and clinically meaningful initial weight loss which was partially sustained after one year. This study confirmed the important role of diet and exercise in short- and long-term weight loss.

CRD commentary

This review was based on defined inclusion criteria for participants, interventions, outcomes and study designs. Searching encompassed a range of sources. Study quality was assessed, although results were not presented in full. It was unclear whether methods to address bias and error were applied to all stages of the review process. Details of the exercise and diet regimes of individual studies were not provided, so it was unclear whether study pooling was appropriate. Results were presented as superior for exercise and diet compared to diet alone, but they were not statistically significant. Although the conclusions appeared self-evident, they did not follow directly from the results presented.

Implications of the review for practice and research

Practice: The authors stated that diet and exercise provided greater weight loss than diet alone, but both types of intervention were associated with long-term weight regain.

Research: The authors stated that future programmes should explore the best strategies to promote long-term changes in lifestyle in relation to diet and exercise. Reasons for study withdrawal should be assessed. Frequency of responses to interventions should be included as outcomes in addition to mean weight loss. Future trials should describe randomisation and blinding processes and include intention-to-treat analyses.

Funding

Not stated.

Bibliographic details

Curioni CC, Lourenco PM. Long-term weight loss after diet and exercise: a systematic review. International Journal of Obesity 2005; 29(10): 1168-1174. [PubMed: 15925949]

PubMedID

15925949

Indexing Status

Subject indexing assigned by NLM

MeSH

Adult; Aged; Combined Modality Therapy; Diet, Reducing; Exercise Therapy /methods; Female; Humans; Male; Middle Aged; Obesity /therapy; Randomized Controlled Trials as Topic; Weight Loss

AccessionNumber

12006000628

Date bibliographic record published

06/12/2007

Date abstract record published

13/10/2010

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 15925949

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