Good introductory book in need of a revision

Despite recent attempts to tone down the severity of the problem, the Western world presently witnesses the highest prevalence of paediatric overweight and obesity ever. Although there are several studies indicating that the increase in prevalence of overweight and obesity has slowed down or even has been terminated, a spontaneous reduction seems highly unlikely. Hence, profound understanding of the problem from many perspectives and the swift implementation of effective and attractive evidence-based interventions are acutely needed.

Since childhood obesity is a field of great interest for clinicians, politicians, the general public and others, a comprehensive book on the issue is definitely warranted. Indeed, Children, Obesity and Exercise edited by Andrew Hills, Neil King and Nuala Byrne is an attempt to cover a wide range of aspects of the area. The topics included vary from methodological issues, over clinical comments, to behavioural, environmental and psychosocial correlations with obesity. Finally, a number of interventions aimed at reducing prevalence or severity of obesity are reviewed.

The important issue of tracking is introduced in the first part of the book. Several important studies are reviewed and the adult consequences of childhood obesity are underlined. Authors conclude that there is a moderate tracking of weight status from childhood, via adolescence into adulthood. Following this is a concise chapter on the clinical aspects of obesity, which lists a number of important co-morbidities together with epidemiological data. Physical activity as an important part of the growth and development of the child is briefly reviewed, and the authors also describe the recommendations for activity. However, considering the lack of valid assessment tools for physical activity, these recommendations must be presented with considerably more critical assessments than is the case here.

Upon this follow a few chapters on methodology. They cover assessment of physical activity, energy intake and body composition, all relevant to the scope of the book. Concerning quantification of physical activity, one of the main shortcomings of the book becomes apparent. Assessment techniques are rapidly developing, but the reference list mainly includes papers published five to ten years before the book was printed. Therefore, the chapter lacks several important publications. This is probably the explanation for the obvious bias between the description of pedometers and accelerometers. The outdated set of references does not affect the description of available techniques for body composition and energy intake assessment to the same extent, since their development rates are somewhat slower.

Two chapters examine the behavioural aspects of physical activity and obesity. The importance of perceived competence in the motivation of obese to be physically active is thoroughly discussed. This chapter is very well written, based on a large number of empirical observations and also including direct recommendations for the implementation of the discussed findings into physical activity interventions. In the light of this, the chapter on psychosocial aspects of childhood obesity seems very indistinct and focuses mainly on yet unproven theories and extrapolations from other areas. Only a few papers with empirical evidence are presented. The important connection between central structural social factors and behaviour is not discussed and rather than suggesting solutions, the authors stop at faintly describing the problem.

Physically active commuting to and from school is a potentially viable form of intervention, which is interesting for several reasons. It is a form of activity that may be easier than others to implement and sustain, due to for example its low intensity and regularity. However, not much evidence for how to physically plan the environment to facilitate active commuting is presented in the chapter discussing this issue. This chapter holds the most updated reference list, so the lack of data is not due to that new papers are absent. Possibly, this is a field where new knowledge is especially needed. Rebuilding the physical environment is obviously very expensive and solid evidence must be presented in order to make decision-makers take the steps needed. It seems to me that this sort of evidence is missing today.

The final chapter discusses interventions. Since this field is growing extremely rapid, an outdated reference list is naturally an Achilles heel. Ideas of how to implement physical activity are proposed in the text, of which several now have been tested and found to be ineffective. Furthermore, as knowledge expands we now know more of how certain sub-groups react to different forms of intervention, something that is absent in the text.

Despite the age of most papers cited, this is a book that I would consider as basic for students in many disciplines, such as physical education, health sciences, medicine, law, political science and others. It has the outline of a review article in several areas.

However, I am missing an epidemiological approach, for example a detailed description of when and where the obesity epidemic started. Further, isolating the risk factor overweight and obesity precludes the possibilities to compare the risk of this to other risk factors. The independent risk of overweight or even obesity is in some studies not associated with any increased risk. It is rather an index of the presence of other risk factors, such as hypertension, diabetes mellitus type II, low levels of physical activity. This fact has direct implications for the design of interventions.

Another comment: In some chapters overweight and obesity are discussed as one and in others, only obesity is discussed. There are several reasons as to why one must be cautious in this case, mainly due to the differing risks and medical consequences associated with overweight vs. obesity, but also since the possibilities for interventions differ.

Take home message: This is a book suitable as a basic book for anyone getting into the area, including students. A revised version, including newer references would improve the texts to a great extent.