Increased adiposity and decreased muscle mass contribute substantially to age-dependent disease and disability. In particular age-related increase in adiposity is quickly becoming a major threat to public health throughout the world. Although the hypothesis that age-related changes in body composition are due to lifestyle choices alone is well accepted, it is a vast oversimplification. This volume reflects the current knowledge in this rapidly developing field of research. The first part of the book discusses the extent to which increased adiposity contributes to age-related diseases and longevity. The 'obesity paradox', describing the protective role of overweight in decreasing mortality while increasing pathology, is covered in depth. Further chapters address specific aspects of the regulation of energy balance during aging, including the effects of changes in food intake. Finally the causes and consequences of loss of muscle mass and age-related osteoporosis are examined. A valuable help for physicians treating elderly patients, this book will also be of great interest to researchers studying energy balance, muscle physiology, bone disease, and other aspects of aging.