Obesity Epidemiology. Frank B Hu.

In the past two decades obesity has become one of the most important public health issues. Obesity epidemiology is a valuable resource for researchers and graduates interested in the causes and consequences of obesity. Although the majority of chapters are written by Dr Frank Hu himself, he invites contributions from experts from the United States many of whom are from the Harvard Medical School or the Harvard School of Public Health, to discuss specific specialist areas in obesity. The book provides a comprehensive and fairly up-to-date account of the evidence on both consequences and determinants of obesity. However, for those interested in treatment and management of obesity and weight loss programs, this book is not written for those purposes. The book is written in three parts with 22 chapters. Part I begins with an overview of obesity epidemiology and focuses on study designs and measurement issues in epidemiological research on obesity. There are seven chapters in this section including a comprehensive and informative chapter on describing the measures of adiposity and body composition used in epidemiological research, ranging from weight and height to bioelectric impedance analysis, and highlighting the strengths and limitations associated with such measurements. There are also chapters on dietary assessment methods and physical assessment methods not usually seen in other obesity text books. Given that obesity is often studied along side with nutrition and physical activity, these chapters provide useful additional material. This section provides good background reading to epidemiological methods in studying obesity and health, how to interpret epidemiological evidence and issues that need to be considered in epidemiological obesity research. There is also a chapter describing obesity trends, but I found this chapter rather biased towards illustrating the evidence from US cohorts rather than worldwide trends. Part II, written in six chapters, provides a review of the metabolic and health consequences of obesity with separate chapters on metabolic consequences of obesity, cardiovascular disease (including stroke and heart failure), cancer, mortality and health-related quality of life. The chapter on metabolic consequences provide a brief overview of the known relationships between obesity and individual components of the metabolic syndrome, biological markers, such as inflammation, endothelial dysfunction, thrombogenic factors and insulin resistance and metabolic diseases. Those interested in metabolic consequences and underlying mechanisms will perhaps find this chapter too concise. This book provides only a brief overview on these topics and does not go into any great detail or in depth review about adipocytokines, adipose tissue or mechanisms underlying the metabolic diseases associated with obesity. Two chapters describe epidemiological studies in obesity and cardiovascular disease and cancer. A chapter on mortality reviews the epidemiological evidence regarding the relationship between different adiposity measures in relation to mortality and touches on the controversy of the U-shaped relationship between BMI and mortality. It discusses the issues of confounding and reverse causation in interpreting the relationship. However, a few important topics are not covered in detail, such as bioelectric impedance analyses or the opposing effects of fat mass and fat-free mass on mortality. The final chapter in this section discusses the economic costs of obesity. Part III, containing nine chapters, focuses on the determinants of obesity including behavioural (physical activity), dietary, social and genetic determinants and covers newer areas in the field of obesity research including sleep deprivation, metabolic and hormonal predictors of obesity. There are two separate chapters discussing in detail the role of diet, nutrition and physical activity and obesity. These two chapters provide a nice review of the evidence from epidemiological studies and clinical trials regarding the effects of physical activity, macronutrients and individual foods on body weight. A further chapter reviews the empirical evidence detailing associations between social determinants (including socioeconomic position, neighbourhood influences and psychosocial factors) and obesity. Chapter 18 provides an overview of metabolic and hormonal predictors of obesity including the role of inflammation and adipokines (leptin and adiponectin). Chapters 19 and 20 in this section (two of the few chapters not written by Dr Frank Hu) are dedicated to childhood obesity; one on developmental origins of obesity and a separate chapter on predictors and consequences of childhood obesity. The final two chapters discuss the role of genetics in obesity. The chapter on genetic predictors of obesity provide very useful background reading to the role of genetics in obesity and a good summary of major genes implicated in obesity. The final chapter reviews the evidence on the gene–environment interaction and obesity. Despite the complexity of genetics these chapters are written in a user-friendly manner. The literature on obesity is vast and inevitably some issues may not have been included. However, perhaps my only one disappointment was that this book does not provide any in depth review on obesity in the elderly which is a very important topic both in terms of the public health implications as well as the epidemiological issues to be addressed in studying the elderly. This has been a topic of increasing epidemiological research given the controversy surrounding the impact of obesity in the elderly. Increase in visceral fat and sarcopenia (loss in muscle mass) with ageing and the limitations of using BMI as a measure of adiposity in the elderly or the topic of sarcopenic obesity is only mentioned in passing. But the book does well to cover most key areas in obesity epidemiology research in just under 500 pages including well-established findings and newer areas of research in obesity, some in greater detail than others. The book was intended as a text book for graduates and it was hoped that it would appeal to a wider audience. It has certainly accomplished its purpose. Overall, obesity epidemiology would be a valuable text book not only for graduates in obesity epidemiology but also would serve as a good background or introductory reading for research epidemiologists and health professionals who have an interest in this field. I found this book interesting with a lot of useful facts and practical information. It will be a good reference book in the field of obesity epidemiology and would make a worthwhile addition to public health and epidemiology department libraries.