Overweight amongst children and adolescents: Methodological aspects of data assessment and interpretation

Overweight amongst children and adolescents is an ever increasing problem in today's society. In order to find appropriate, evidence-based solutions to this problem information on the origins and causes of this increase are required. Much of what we know today has come from observational, epidemiological studies. However, limitations inherent in the study design and data collection methodology specific to these studies, have resulted in gaps in our information, as well as in possible misinterpretations. It is methodologically very difficult to accurately measure energy consumption, especially in children and adolescents. The reasons for this lie, on the one hand, in the degree of intra- and inter-individual variability in eating behaviour, and on the other, in the negligible absolute differences in energy consumption between individuals who maintain a stable body weight and those who put on weight. The assumptions which often guide the interpretation of data appear to be inconclusive, and this fact, together with the aforementioned difficulties, creates the impression that nutrition has only a secondary role to play in the increasing prevalence of overweight. Using concrete data examples and well-known criticism of methodology we intend to show why/how the role of nutrition in the increasing prevalence of over-weight might be underestimated.