Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies
BMJ 2013; 346 doi: https://doi.org/10.1136/bmj.e7492 (Published 15 January 2013) Cite this as: BMJ 2013;346:e7492
- 1Departments of Human Nutrition and Medicine, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- 2Riddet Institute, University of Otago
- 3Edgar National Centre for Diabetes and Obesity Research, University of Otago
- Correspondence to: J Mann jim.mann{at}otago.ac.nz
- Accepted 28 October 2012
Abstract
Objective To summarise evidence on the association between intake of dietary sugars and body weight in adults and children.
Design Systematic review and meta-analysis of randomised controlled trials and prospective cohort studies.
Data sources OVID Medline, Embase, PubMed, Cumulative Index to Nursing and Allied Health Literature, Scopus, and Web of Science (up to December 2011).
Review methods Eligible studies reported the intake of total sugars, intake of a component of total sugars, or intake of sugar containing foods or beverages; and at least one measure of body fatness. Minimum duration was two weeks for trials and one year for cohort studies. Trials of weight loss or confounded by additional medical or lifestyle interventions were excluded. Study selection, assessment, validity, data extraction, and analysis were undertaken as specified by the Cochrane Collaboration and the GRADE working group. For trials, we pooled data for weight change using inverse variance models with random effects. We pooled cohort study data where possible to estimate effect sizes, expressed as odds ratios for risk of obesity or β coefficients for change in adiposity per unit of intake.
Results 30 of 7895 trials and 38 of 9445 cohort studies were eligible. In trials of adults with ad libitum diets (that is, with no strict control of food intake), reduced intake of dietary sugars was associated with a decrease in body weight (0.80 kg, 95% confidence interval 0.39 to 1.21; P<0.001); increased sugars intake was associated with a comparable weight increase (0.75 kg, 0.30 to 1.19; P=0.001). Isoenergetic exchange of dietary sugars with other carbohydrates showed no change in body weight (0.04 kg, −0.04 to 0.13). Trials in children, which involved recommendations to reduce intake of sugar sweetened foods and beverages, had low participant compliance to dietary advice; these trials showed no overall change in body weight. However, in relation to intakes of sugar sweetened beverages after one year follow-up in prospective studies, the odds ratio for being overweight or obese increased was 1.55 (1.32 to 1.82) among groups with the highest intake compared with those with the lowest intake. Despite significant heterogeneity in one meta-analysis and potential bias in some trials, sensitivity analyses showed that the trends were consistent and associations remained after these studies were excluded.
Conclusions Among free living people involving ad libitum diets, intake of free sugars or sugar sweetened beverages is a determinant of body weight. The change in body fatness that occurs with modifying intakes seems to be mediated via changes in energy intakes, since isoenergetic exchange of sugars with other carbohydrates was not associated with weight change.
Footnotes
We thank Carolyn Summerbell and Bernard Venn for their help on the initial development of this research; Melissa Butt and Sarah Harvey, who contributed to the data search for the randomised controlled trials; Marcus Du, who contributed to the data search and extraction for the cohort studies; and the members of the WHO NUGAG Subgroup on Diet and Health for their contribution to this work.
WHO agreed to the publication of this systematic review in a scientific journal, because it serves as the background evidence review for updating WHO guidelines on total sugars intake and should therefore, be available widely.
Contributors: The questions for the review were discussed and developed by the WHO NUGAG Subgroup on Diet and Health in February 2010, and the protocol was approved by the NUGAG Subgroup on Diet and Health. LT and SM supervised study searches. LT, SM, and JIM assessed inclusion, extracted data, and assessed validity. LT did the meta-analyses. LT and JM wrote the manuscript. The NUGAG Subgroup on Diet and Health reviewed the first draft of the report and contributed to the GRADE assessment. All authors read and approved the final draft of the report.
Funding: The authors were supported by the University of Otago and the Riddet Institute, a New Zealand National Centre of Research Excellence. The research was supported by the University of Otago, Riddet Institute, and WHO. The authors undertook the submitted work for WHO for the purposes of updating WHO guidelines on sugars intake, and WHO provided some funding to the University of Otago towards the cost of carrying out the review.
Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: support from the University of Otago, Riddet Institute, and WHO; no other financial relationships with any organisations that might have an interest in the submitted work in the previous 3 years; and no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: Not required.
Data sharing: No additional data available.
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