Authors’ reply to Cottrell and Wittekind

Our meta-analysis was mainly intended to determine the effect on body weight of increased or decreased intake of sugars or food and drink containing sugars in free living people.1 2 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 changes in protein, fat, and energy intake occurred, but rather than confound our results, this enabled us to answer the practical question we had posed.

Saris and colleagues compared three diets.3 Cottrell and Wittekind seem to have assumed that we compared the high sugar diet with the “control” diet.2 This was not the case. The “control” group followed a relatively high fat diet. Given the questions under examination, we appropriately compared the two other diets that had similar proportions of fat and total carbohydrate—one was higher and the other lower in sugars. Comparison with the group consuming more fat was not germane to the meta-analysis.

Heterogeneity, potential publication bias, and absence of a dose-response effect were all discussed in our paper. However, weight change was remarkably similar when sugar intake was increased or decreased over relatively short periods. In addition, there was a suggestion that the effect was more marked when dietary change was implemented over a longer period. These results all suggest that advice to limit sugar intake might usefully be included in the raft of measures needed to battle the global epidemic of obesity.