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

BMJ 2013; 346 doi: (Published 15 January 2013) Cite this as: BMJ 2013;346:e7492

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

The meta-analysis was primarily intended to determine what effect on body weight might be expected should free-living individuals increase their intake of sugars or foods and drinks containing sugars, or be advised to decrease their intake. It was therefore appropriate to exclude studies in which changes in other dietary or exercise practices were recommended, and to include studies where total energy intake was not prescribed. Inevitably in such studies some change in protein, fat and energy occurred, but rather than confound our results, this enabled us to answer the practical question we had posed.

Saris et al. (2000) compared three diets. Dr Cottrell appears to have assumed that we compared the high sugars diet with the “control” diet. This was not the case. The “control” group followed a relatively high fat diet. Given the issue under examination, we appropriately compared the two other diets with similar proportions of fat and total carbohydrate; one being relatively higher and the other relatively lower in simple carbohydrate (sugars). Comparison with the group consuming a higher fat intake was not germane to the meta-analysis.

The heterogeneity, potential publication bias, and absence of a dose response effect are all discussed in our paper. However, the remarkably similar weight change when intake of sugars is increased or decreased over relatively short periods and the suggestion that the effect is more marked when dietary change is implemented over a longer period suggests that advice to limit sugars intake might usefully be included amongst the raft of measures needed to battle the global epidemic of obesity.


Saris WHM, Astrup A, Prentice AM, Zunft FJF, Formiguera X, Verboeket-van de Venne WPHG, Raben A, Poppitt SD, Seppelt B, Johnston S, Vasilaris TH, Keogh GF (2000) Randomized controlled trial of changes in dietary carbohydrate/fat ratio and simple vs complex carbohydrates on body weight and blood lipids: the CARMEN study. International Journal of Obesity 24:1310-1318.

Competing interests: No competing interests

24 February 2013
Lisa Te Morenga
Research Fellow
Jim Mann, Simonette Mallard
University of Otago
PO Box 56 Dunedin, 9054 New Zealand