What is obesity?
What is obesity?

Overweight means that a person weighs more than they should for a given height. Obesity is a condition where a person is so overweight that it is unhealthy. People who are overweight or obese are more likely to get certain diseases and have other health problems.

Body Mass Index (BMI) relates to the amount of body fat a person has. BMI is a mathematical formula. It uses height and weight to compare people of different heights. A BMI greater than 27 means overweight and a BMI of 30 or greater means obese. For children and teens, BMI also takes into account normal differences in body fat between boys and girls and differences at various ages.

There are other ways to determine obesity. Skinfold thickness, the size of your waist, and special ultrasounds are also used.

Other methods of measuring BMI

Method of measurement How BMI is measured
Skinfold thickness Skinfolds are measured in different parts of the body with a pincher to determine how much fat is under the skin. The measurement is then calculated to determine body fat percentage.
Waist Circumference The waist is measured to determine excessive abdominal fat; a man’s waist over 40 inches and a non-pregnant woman’s waist over 35 inches have a higher risk of developing obesity-related conditions.
Special Ultrasound Non-invasive ultrasounds are used to measure the thickness of body fat under the skin.

Based on information from CDC.gov, InteliHealth, and the Journal of Athletic Training

To learn more:

Defining Obesity and Overweight
(Centers for Disease Control and Prevention)
Defines obesity and overweight and describes how they are determined.
Obesity Overview
Provides a brief overview of obesity and suggests plans for losing weight.
Understanding Adult Obesity
(Weight-control Information Network, National Institute of Diabetes and Digestive and Kidney Disease)
Defines obesity: causes, risks and effects, and some treatments.
Adult BMI Calculator
(Centers for Disease Control and Prevention)
Input your height and weight to find out if you are overweight or obese.

next » What causes obesity?

Written by: Maya Hollinshead B.A.
Reviewed by: Jeffrey G. Schultze, M.D.
Last Modified: Friday April 02, 2010 12:41 PM