Book excerpt: The Federal guidelines on the identification, evaluation, and treatment of overweight and obesity in adults have defined "overweight" as a body mass index value between 25 and 29.9; and "obesity" as a body mass index value greater than or equal to 30. BMI is a ratio between weight and height. It is a mathematical formula that correlates with body fat, used to evaluate if a person is at an unhealthy weight (given a certain height). BMI value is more useful for predicting health risks than the weight alone (for adults ages 18 and up). Individuals with high BMI's are at increased risk of developing certain diseases, including: Hypertension, Cardiovascular Disease, Dyslipidemia, Adult-Onset Diabetes (Type II), Sleep Apnea, Osteoarthritis, Female Infertility, and other Conditions, including: idiopathic intracranial hypertension lower extremity venous stasis disease, gastroesophageal reflux and urinary stress incontinence. This new book gathers research from around the world in the critical field of obesity research and its effects.