BMI is a ratio of your weight to your height.
Nearly all adults with a high BMI have extra body fat; those with a low BMI often have too little body fat.
A normal BMI for kids and teens depends on age, and is not the same for adults over age 18.
Diagnostic Status and Risk According to Body Mass Index (BMI).*
For adults over age 18.
|Status||BMI Category (kg/m2)||Risk of developing health problems**|
|Normal Weight||18.5 - 24.9||Least|
|Overweight||25.0 - 29.9||Increased|
|Obese Class I||30.0 - 34.9||High|
|Obese Class II||35.0 - 39.9||Very high|
|Obese Class III||≥40.0||Extremely high|
*Note: Exceptions: For persons 65 years and older the 'normal' range may begin slightly above BMI 18.5 and extend into the 'overweight' range; very muscular athletes and body builders often have high BMIs and are not overfat; children and teens, who need an age appropriate scale; and pregnant and lactating women.
**If your risk is increased, speak with your doctor about having your cholesterol, triglycerides, blood sugar and blood pressure levels as part of a full cardiovascular and diabetes screen.
Adapted from: World Health Organization. (2000). Obesity: Preventing and Managing the Global Epidemic: Report of a WHO Consultation on Obesity. Geneva: WHO, page 9