Overweight and obesity are both labels for ranges of weight that are greater than what is generally considered healthy for a given height. The terms also identify ranges of weight that have been shown to increase the likelihood of certain diseases and other health problems.

For Adults

For adults, overweight and obesity ranges are determined by using weight and height to calculate a number called the "body mass index" (BMI). BMI is used because, for most people, it correlates with their amount of body fat.

* An adult who has a BMI between 25 and 29.9 is considered overweight.
* An adult who has a BMI of 30 or higher is considered obese.

See the following table for an example.

For Height - 5' 9"

Weight Range - BMI - Considered
124 lbs or less Below 18.5 Underweight
125 lbs to 168 lbs 18.5 to 24.9 Healthy weight
169 lbs to 202 lbs 25.0 to 29.9 Overweight
203 lbs or more 30 or higher Obese

It is important to remember that although BMI correlates with the amount of body fat, BMI does not directly measure body fat. As a result, some people, such as athletes, may have a BMI that identifies them as overweight even though they do not have excess body fat.

Other methods of estimating body fat and body fat distribution include measurements of skinfold thickness and waist circumference, calculation of waist-to-hip circumference ratios, and techniques such as ultrasound, computed tomography, and magnetic resonance imaging (MRI).

For Children and Teens

For children and teens, BMI ranges above a normal weight have different labels (at risk of overweight and overweight). Additionally, BMI ranges for children and teens are defined so that they take into account normal differences in body fat between boys and girls and differences in body fat at various ages. For more information about BMI for children and teens are also called BMI-for-age.