Obesity in the United States and worldwide has risen steadily, and alarmingly, since 1960 which has led medical and public health officials to call the situation an epidemic. To further understand obesity we must first look at body composition. Body weight is the sum of the weight of the fat and the weight of the lean body mass. Lean body mass is comprised of all the nonfat body components including muscle, bone, and internal organs. Body composition then is the proportion of body weight that is fat compared to lean. Having a high body weight can be attributed to large muscles or excess fat. A high body weight due to excess fat increases the risk of chronic health problems which can include high blood pressure and cholesterol, heart disease, stroke, diabetes, respiratory problems, arthritis, sleep disorders, and gallbladder disease. Obesity can also increase the risk of breast and uterus cancers in women and prostate and colon cancers in men (Grosvenor,M. & Smolin, L., 2006). There are several factors that weigh into the obesity epidemic. The genes that you inherit from your parents determine your body shape and composition. Obesity genes get their name because an abnormality in one or more of them can result in obesity. There are also different hormones in the body that signal the body to eat or not to eat and have a hand in how much we eat at each sitting. For example the hormone ghrelin is released by the stomach and is believed to motivate you to eat at regular meal times during the day. Insulin is another hormone that helps the body monitor how much fat is present and sends appetite suppressing signals to the brain when fat levels are high. In addition to the genetic factors, there are also lifestyle factors that affect if a person is obese. Overweight people are generally less active. This is not just in terms of planned exercise such as running or biking, but also in day-to-day activities such as housework or walking to and from your car. The most glaring difference is that as a society Americans are eating more than we used to. Some of that has to do with the availability of food being more convenient than ever. There is an abundance of 24-hour stores and restaurants that are serving larger and larger portions. Additionally people are eating beyond when they feel full and letting their appetite control what they eat instead of hunger. As well as eating more, most Americans are exercising less (Grosvenor,M. & Smolin, L., 2006). An eating disorder can develop when a person becomes overly concerned with eating, food, and body size and shape. There are three categories of eating disorders; anorexia nervosa, bulimia nervosa, and binge-eating disorder. Anorexia nervosa is the desire to be thin which causes individuals to reduce their food intake. The physical symptoms of anorexia are the same as starvation. These symptoms start with weight loss and include wasting of muscles, flaking and peeling skin, dry thin brittle hair that can fall out, and inflammation and swelling of the lips. Anorexia also affects mental function causing the person to become apathetic, exhausted, and depressed. Treatment for anorexia includes treating the psychological issues while restoring physical and nutritional deficiencies that starvation has caused. Bulimia nervosa is characterized by episodes of binge eating that are followed closely by purging and other compensatory behaviors. Bulimia is broken into two categories; purging and nonpurging types. People that suffer from bulimia have a fear of becoming fat along with a negative body image and distorted perception of their bodies just like anorexics. Chronic bulimics can cause damage to the GI tract in the form of tooth decay, sores in the mouth, swollen jaws, irritation of the throat, and esophageal inflammation from vomiting. The goal of treatment for bulimics is to separate eating from their emotions. Binge eating disorder is characterized by binge eating episodes without the purging afterward. This is the most common eating disorder among Americans and also affects men and women equally (Grosvenor,M. & Smolin, L., 2006).

References
Grosvenor, M. B., & Smolin, L. A. (2006). Nutrition: Everyday choices. Hoboken, New Jersey: John Wiley & Sons.