A large share of the population in many developing countries suffer from chronic undernutrition. In this book, Professor Svedberg provides a detailed comparative study of undernutrition in Sub-Saharan Africa and South Asia, the two worst affected areas, and provides crucial advice for all those concerned in development worldwide. The book concentrates on the five challenges that undernutrition creates: what undernutrition is, who the undernourished are, where the undernourished are, when people are undernourished, and why people are undernourished. The book is divided into five parts: Part I introduces the main paradigms and controversies of undernutrition; Part II deals with the relationship in the individual between calorie intake/expenditure, work effort, body weight, and income; Part III assesses the method of defining and measuring undernutrition based on estimates of gaps between calorie intake and calorie requirements for households; Part IV provides a parallel analysis of the main alternative approach to defining and measuring undernutrition, based on anthropometric assessment, mainly of young children, but also adolescents and adults; Part V analyses the consequences and causes of anthropometric failure, as well as the related policy issues.