Author contributions: S. A. J. had the idea for the paper. L. J. wrote the first draft of the paper. L. J., D. C. W. and A. K. L. performed the systematic review. All authors were responsible for critical revisions to the paper and approval of the final manuscript. This publication is the work of the authors, all of whom will serve as guarantors for the contents of this paper.
Reflections from a systematic review of dietary energy density and weight gain: is the inclusion of drinks valid?
Article first published online: 21 APR 2009
© 2009 The Authors. Journal compilation © 2009 International Association for the Study of Obesity
Volume 10, Issue 6, pages 681–692, November 2009
How to Cite
Johnson, L., Wilks, D. C., Lindroos, A. K. and Jebb, S. A. (2009), Reflections from a systematic review of dietary energy density and weight gain: is the inclusion of drinks valid?. Obesity Reviews, 10: 681–692. doi: 10.1111/j.1467-789X.2009.00580.x
- Issue published online: 28 OCT 2009
- Article first published online: 21 APR 2009
- Received 29 September 2008; revised 19 January 2009; accepted 16 February 2009
- Dietary energy density;
- weight gain
The association between dietary energy density, increased energy intake and weight gain is supported by experimental evidence, but confirmation of an effect in free-living humans is limited. Experimental evidence supports a role of energy density in obesity through changes in food composition, not drinks consumption. The inclusion of drinks in the calculation creates a variable of questionable validity and has a substantive impact on the estimated energy density of the diet. We posit, based on the experimental evidence, that calculating the energy density of diets by excluding drinks and including calories from drinks as a covariate in the analysis is the most valid and reliable method of testing the relationship between energy density and weight gain in free-living humans. We demonstrate, by systematically reviewing existing observational studies of dietary energy density and weight gain in free-living humans, how current variation in the method for calculating energy density hampers the interpretation of these data. Reaching an a priori decision on the appropriate methodology will reduce the error caused by multiple comparisons and facilitate meaningful interpretation of epidemiological evidence to inform the development of effective obesity prevention strategies.