Obesity

Definition of Obesity
Article updated and reviewed by Hubert Chen, MD, Associate Director of Medical Sciences, Amgen Inc. and Assistant Professor of Clinical Medicine University of California, San Francisco on July 8, 2005.
Obesity refers to an increase in total body fat. The easiest and most widely accepted method of determining whether you are obese is by measuring your Body Mass Index, orBMI. To calculate your BMI, follow these steps:
1. Multiply your weight in pounds by 705; divide by your height in inches; divide this number by your height in inches a second time.
2. You may also use an online BMI calculator at the National Heart, Lung, and Blood Institute. Go to http://www.nhlbisupport.com/bmi/.
A normal BMI = 18.5-24.9; overweight = 25.0-29.9; obese = 30 or greater; andmorbidly obese = 40 or greater.
Why Should I Care About Obesity?
Obesity has become an epidemic in the U.S. and other developed countries. As many as one-third of all Americans are obese based on the BMI criteria. In addition to body image issues, obesity causes significant health issues. It is the second leading cause of preventable death (after smoking), and is associated with type 2diabetes, hyperlipidemia, coronary artery disease, arthritis, gallstones, and certain types of cancer.
Description of Obesity
Often referred to as a disease, obesity is actually a sign of what may well be a spectrum of different kinds of disorders � genetic or environmental. In fact, there is no single definition of obesity. It may be simply an extreme degree of overweight - but a person can beoverweight without being obese. A 250-pound, 6' linebacker, for example, may be overweight according to ordinary standards, but may actually have a below-average amount of body fat. In contrast, a person in a normal weight range but with very sedentary habits, could have a small muscle mass, be storing excess fat, and thus be classifiable as obese.
About one-half of all Americans are above theirideal weight, as determined by standard tables, and for the majority of them, the excess weight is in the form of body fat, not muscle mass. Of this group, half exceed their ideal weight by 20 percent or more. Hence, they are classified as obese.
Obesity has become epidemic in the U.S. and other developed countries. More than 58 million Americans are overweight, and that includes at least 1 in 5children.
Two principal risk factors that lead to obesity, poor nutrition and lack of physical activity combined, are the second leading cause of preventable death (tobacco is first). Obesity is associated with significant increases in risk for type II diabetes mellitus, hyperlipidemia, high cholesterol, coronary artery disease, degenerative joint disease and psychosocial disability. Certaincancers - colon, rectum and prostate in men; uterus, biliary tract, breast and ovary in women - are more prevalent in the obese.
Causes and Risk Factors of Obesity
Until recently, obesity was considered the result of a sedentary lifestyle and the chronic ingestion of excess calories. This may be the principal factor for many individuals, but there is evidence of strong genetic, metabolic, andenvironmental influences in the development of obesity. Certain illnesses, such as Cushing�s syndrome or hypothyroidism, and medications, such as glucocorticoids, can also cause obesity. However, less than one percent of all obese patients have an identifiable secondary cause of obesity.
Diagnosis of Obesity
A physical examination, including a measurement of weight and height, is usuallysufficient to diagnose obesity. A complete medical history, including age of onset, family history, eating and exercise behavior, smoking, alcohol use, and previous weight loss experience are all important.
Your physician may order blood tests, including fasting levels of glucose, cholesterol and triglycerides, to determine whether any obesity-related conditions are present.
Treatment of Obesity...