Preface

Total body weight is the sum of the weight of all body components. Among these components, water, adipose tissue, muscle, and bone are the main contributors. The physiological or pathological variations in the amount or mass of each component can lead to an increase or decrease in total body weight. Some of these changes carry a risk of increased morbidity and mortality. The variations in body weight are increase (retention) or decrease (dehydration) in water amount, increase (hypertrophy, hyperplasia) or decrease (lipodystrophy) in adipose tissue mass, increase (hypertrophy) or decrease (sarcopenia) in muscle mass, and increase (increased bone density) or decrease (osteopenia, osteoporosis) in bone mass. A variety of factors including genes, lifestyle, environment, age, diseases, and medications can promote these conditions. The most common and relevant body weight change is obesity, which is a major health problem worldwide. The prevalence of obesity has doubled in more than 70 countries since 1980. The number of adults with obesity is around 650 million worldwide. This book provides the reader with a comprehensive overview of current knowledge about the pathophysiology, consequences, complications, and treatment of different types of body weight changes, with a special emphasis on obesity.

The book contains thirteen chapters by authors from Dominica, France, India, Nigeria, Qatar, Ukraine, South Africa, the United Kingdom, and the United States. I would like to thank all of them. I would also like to express my appreciation for the great assistance provided by Ms. Ana Javor at IntechOpen who supervised this book project.

> **Hassan M. Heshmati, MD** Endocrinology Metabolism Consulting, LLC, Anthem, AZ, USA

**1**

Section 1

Leptin Pathophysiology

Section 1
