When one of us first started working with overweight and obese children in the early 1970s the admission that she ran an obesity clinic for children was greeted with wry amusement or the comment ‘You don't achieve anything do you?’ Today the prevalence of childhood overweight and obesity in not only the UK but most westernized societies and increasingly in less affluent countries too has changed this attitude. The comment is now not whether we achieve anything but an imperative that we must achieve something if we are to prevent the present generation of young people having lifetimes of high morbidity and mortality as consequences of their excessive fatness. Yet, for all the concern about obesity, there is no ‘magic bullet’, ‘wonder diet’ nor consensus view on how to manage the condition. This book does not pretend to answer that dilemma but to present guidance which we hope will support those trying to help these children.

Throughout the book we use both overweight and obesity, often together, to describe children who are likely to have significant increases in percentage of body weight as fat. The mixed terminology relates to the fact that most children are diagnosed as ‘obese’ because they have a high body weight and thus an abnormal relationship between weight and height for age (whatever method is used). Technologies that have been developed to be more specific about body composition in most cases do not directly measure fat in the body (see Chapter 2).