Dr. Schaafsma has proposed some questions regarding the DRINK study.
Scherpenzeel, 4 October 201209-10-2012 Questions of Gertjan Schaafsma, PhD, concerning study on soft drinks and overweight in children
Dear Janne,
It is with much interest and appreciation that I took cognizance of your solid and important study on soft drinks and overweight in children, which was published two weeks ago on line in the NEJM. You may understand that certain stakeholders followed the results of this study with more than usual interest. This is for instance the case for the Sugar Foundation in the Netherlands. This organization, which is sponsored by the Dutch sugar industry, disseminates nutrition information on the role of sugar in the diet and financially supports research in this area. As an independent scientist I give advices to this organization. On its web site the foundation has paid attention to your study and asked me to review critically your study. I did that. As a consequence I have some questions that, according to my view, were not clearly answered in your paper. I like to take the opportunity to ask you these questions with the kind request to answer them.
You put forward that in the case of complete compliance a weight difference of 2.3 kg between test- and control group could be expected. That difference is much smaller than one would expect at an energy intake difference of 100 kcal/day during 1.5 years. It is difficult to imagine that the large majority of this energy intake difference is used for the small difference in resting metabolic rate and for the extra energy required for activity at a higher body weight. Can you explain this in a quantitative way.
The observed weight difference (ample 1 kg) was considerably lower than the expected 2.3 kg. This could only partly be explained by the incomplete compliance. You do not give a clear explanation for this considerably lower result. To what extent is energy compensation involved here? Is it possible that the test group increased its food intake and/or that the control group reduced its food intake on the longer term? In this regard it is remarkable that the largest part of the result was achieved already in the first 6 months of the study.
The weight difference of 1 kg consisted for about 500 g of fat. The rest was LBM. After correction for the higher body height of the control group, the weight difference was 0.83 kg. Must I conclude that the difference in body fat after correction for the body height difference was also smaller? Nothing is said about this in your paper. I suppose that correction for the height difference may not result in a change of the BMI. Then there is no other possibility that the body composition (in %) must remain the same and thus that after weight reduction (kg) the amount of fat must decrease (to about 400 g). The amount of 400 g is better in line with both the skin fold- and TBI measurements.Or am I wrong?
To my opinion the most simple explanation for the observed results is that considerable energy compensation has taken place. If this view is correct, then one cannot conclude on the basis of this study that sugar in drinks does not satiate.
I would appreciate very much receiving your response.
With best regards,
Gertjan Schaafsma PhD
Schaafsma Advisory Services in food,
health and safety
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3925 VD Scherpenzeel
The Netherlands
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