Overview

Definition

Obesity is a chronic disease affecting millions of Americans. It is defined by excess body fat and is generally measured by calculating a person's BMI (body mass index). If a person's BMI is 30 or above, he or she is considered to be obese. The concern of health care providers about people being obese isn't because our society places an emphasis on being thin. Rather, being obese means that you're carrying too much weight for your height. The additional weight puts stress on your body that can adversely affect your health.

Obesity is a major risk factor for coronary heart disease, high blood pressure, stroke, diabetes and some forms of cancer. Obese people are also at high risk for depression, job discrimination and other social problems. Some 300,000 premature deaths are caused by obesity each year, and about $100 billion in annual health care costs is attributed to obesity. After tobacco use, obesity is the second-leading cause of preventable deaths. About six out of 10 Americans are overweight or obese, and those numbers are rising. The number of children and teens who are overweight or obese is also expected to increase.

To determine if you are obese, your doctor uses a formula to determine your BMI.

Here's how to calculate BMI:

A person who weighs 220 pounds and is 6 feet 3 inches tall has a BMI of 27.5.

Obesity would most likely be diagnosed in the following cases:

• A 6-foot-tall individual who weighs 221 pounds.
• A 5-foot, 5-inch-tall person who weighs 180 pounds.

Anyone whose BMI is 40 or higher is considered severely (morbidly) obese. Severe obesity would probably be diagnosed in the following cases:

• A 5-foot, 3-inch-tall person who weighs 226 pounds.
• A 6-foot, 1-inch person who weighs 303 pounds.

Waist circumference measurement for obese people helps determine health risks related specifically to abdominal fat. Men and women with apple shapes (weight mostly in the belly area) are particularly at risk. Measure your waist size by wrapping a tape measure around the area above your hip bone and below your rib cage.

• Men at high risk for diseases have a waist measurement greater than 40 inches.
• Women at high risk have a waist measurement greater than 35 inches.

Prognosis: Obesity does not have a magic pill, but diet and exercise can help reduce weight. However, that might not always be enough. Surgery or medication may also be used along with diet and exercise.

More on Obesity

This article was reviewed and updated June 2007.