What is Obesity?

Obesity is generally defined as being 20 percent or more over ideal body weight. Over time, there have been a number of systems used to measure obesity. For example, the Metropolitan Life Insurance Company created tables (see below) years ago to help predict ideal body weight and provide an estimate of body fat composition. While useful, these tables do have limitations.

Currently, the body mass index (or BMI) is considered the best available indicator of excess body weight. BMI is calculated by dividing an individual’s weight in kilograms by the square of the height in meters. Your weight in pounds can be converted to kilograms by dividing it by 2.2; your height in inches can be converted to meters by multiplying it by 0.0254. (Use our BMI calculator)

Someone who is 20 percent or more over their ideal body weight typically has a BMI of 30 kg/m2 or higher. Clinically severe (or morbid) obesity is considered to be 100 pounds or more over ideal body weight, corresponding to a BMI of 40 kg/m2. People with a BMI greater than 35 kg/m2 and serious health problems related to obesity are also categorized as having clinically severe obesity.

Height & Weight Table for Women

Height & Weight Table for Men

Data courtesy of the Metropolitan Life Insurance Company

Currently, the body mass index (or BMI) is considered the best available indicator of excess body weight. BMI is calculated by dividing an individual’s weight in kilograms by the square of the height in meters. Your weight in pounds can be converted to kilograms by dividing it by 2.2; your height in inches can be converted to meters by multiplying it by 0.0254.

Someone who is 20 percent or more over their ideal body weight typically has a BMI of 30 kg/m2 or higher. Clinically severe (or morbid) obesity is considered to be 100 pounds or more over ideal body weight, corresponding to a BMI of 40 kg/m2. People with a BMI greater than 35 kg/m2 and serious health problems related to obesity are also categorized as having clinically severe obesity.

What is the significance of the BMI?

BMI is used to predict which patients are at the highest risk for weight-related medical problems and identify which patients would benefit most from procedures designed to help them lose weight.

People with clinically severe obesity are at a much greater risk of serious health problems and death than those of the same age at ideal body weight. Some examples of the medical problems that occur more frequently in people with BMIs over 35-40 kg/m2 are:

Other problems related to obesity can include depression, low self-esteem, physical disability, social discrimination and unemployment—to name only a few.