Book Review

Obesity in Youth: Causes, Consequences, and Cures

N Engl J Med 2009; 360:2796June 25, 2009

Article

Obesity in Youth: Causes, Consequences, and Cures
Edited by Leslie J. Heinberg and J. Kevin Thompson. 243 pp. Washington, DC, American Psychological Association, 2009. $59.95. ISBN: 978-1-4338-0427-4

The title and subtitle of this book promise a comprehensive examination of an important public health problem. However, the editors immediately disabuse readers of this notion by stating that the book is focused on the psychosocial aspects of obesity in youths, in contrast with previous works that have focused on the physical health problems. Despite the misleading title, the editors have assembled an impressive group of contributors who cover the psychosocial and behavioral aspects of childhood obesity quite well.

The causes of childhood obesity are addressed in the first section of the book, starting with a review of the genetic bases of obesity. The study of these bases is a young field with exciting implications for individualized assessment and management of obesity and its coexisting conditions. The authors of a chapter on early patterns of physical activity, sedentary behavior, and diet conclude that the reduction of time spent watching television can have beneficial effects on body weight. However, the exact dietary components and types of physical activity that should be recommended are less well understood. The third chapter in this section is an excellent examination of the social and interpersonal influences on behaviors that relate to weight, including the roles of families, peers, and the media.

The second section of the book is an especially valuable contribution on the psychosocial effects of excess body weight, such as stigmatization, mistreatment by peers, depression, damaged self-esteem and body image, and eating disorders. Many useful suggestions for research and clinical practice are provided. The third section includes a chapter on clinical intake procedures for overweight youths that can help in the design of treatment programs, as well as valuable chapters on behavioral approaches to the treatment and prevention of overweight. The book ends with a useful chapter, written by editors Leslie Heinberg and J. Kevin Thompson, on future directions for research on the prevention and treatment of childhood obesity.

One shortcoming that limits this book's usefulness relates to the definition of obesity. Hardly any mention is made of the idea that the health problem that needs to be addressed is an excess of fat mass (or visceral fat), and that an index such as body-mass index (BMI) that is based on the relationship between height and weight is only a surrogate for fatness. BMI has great epidemiologic utility because it is highly correlated with total body fatness and is easily measured; thus, it is widely used in the assessment of population trends. Indeed, it is just this sort of investigation that has alerted us to the worrisome increases in obesity during the past few decades.

However, the classification of elevated BMI as identical to fatness is an unfortunate trend, because some preventive or therapeutic interventions have differential effects on fat and fat-free mass. Moreover, youths with relatively large amounts of fat-free mass have higher resting metabolic rates and higher total expenditures of energy, which allow them to ingest large amounts of food without necessarily becoming obese. A related weakness of the book is the lack of attention to the intensity of physical activity. There is some evidence that vigorous physical activity (e.g., soccer, basketball, dancing) is more clearly associated with lower amounts of body fat than is moderate exercise (e.g., walking to school). Moreover, interventions that involve increases of vigorous physical activity have a beneficial effect on the balance of fat and fat-free mass in both obese and nonobese youths. To formulate and implement interventions that are effective in enhancing the health and well-being of our youth, we need to understand the precise behaviors that are responsible for excess fatness.

Notwithstanding these limitations, this book is a valuable addition to our understanding of the psychosocial and behavioral aspects of obesity in youth.

Bernard Gutin, Ph.D.
University of North Carolina, Chapel Hill, NC 27516
bernardgutin@yahoo.com