Overview of Obesity Obesity is a serious, chronic disease that can inflict substantial harm to a person’s health. Learn about obesity causes and obesity health effects. Determining Your Body Mass Index Your BMI gives a fairly accurate assessment of how much of your body is composed of fat. What's Your Healthy Weight? In today's society, there's much confusion over what constitutes a healthy weight. Here are some ways to find out where you stand on the weight issue. Preventing Obesity Given the chronic diseases and conditions associated with obesity and the fact that obesity is difficult to treat, prevention is extremely important.