Food and Behaviour Research

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Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies

Te Morenga L, Mallard S, Mann J. (2013) BMJ 346  e7492 (Published online 15 January 2013) 

Web URL: View this and related abstracts via PubMed here. Free full text of this article is available online.

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

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.

FAB RESEARCH COMMENT:

This new meta-analysis shows that increased dietary intakes of sugar - whether added to foods, or in sugar-sweetened drinks - are associated with increased body weight, at least in adults.

(The available data for children showed similar trends, but in treatment trials their ability to reduce their sugar consumption was apparently so poor that no meaningful results could be obtained - a result which speaks volumes in itself).

This study forms only one small piece of the accumulating evidence that excessive sugar consumption is harmful to health in many ways - and not just for its contribution to the obesity epidemic.  See 'Science Souring on Sugar' and 'Sugar and the Heart - Old Ideas Revisited'.

These findings support the arguments put forward by obesity expert Robert Lustig, whose new book 'Fat Chance - the Bitter Truth About Sugar' builds on the seminal work of John Yudkin, as summarised in his classic book of 40 years ago 'Pure, White and Deadly'

See also:

Sugar, Fat and the Public Health Crisis

Sugar and the Brain: Food Choice, Addiction and the Mental Health Crisis