Defining Adult Overweight & Obesity

Adult Body Mass Index

BMI is calculated by dividing a person’s weight in kilograms by their height in meters squared. A high BMI may indicate excessive body fat.

To determine BMI, use the Adult BMI Calculator or locate your height and weight on the BMI Index Chart.

If your BMI is less than 18.5, it falls within the underweight range.
If your BMI is 18.5 to <25, it falls within the healthy weight range.
If your BMI is 25.0 to <30, it falls within the overweight range.
If your BMI is 30.0 or higher, it falls within the obesity range.

Obesity is frequently subdivided into categories:

Class 1: BMI of 30 to < 35
Class 2: BMI of 35 to < 40
Class 3: BMI of 40 or higher. Class 3 obesity is sometimes categorized as “severe” obesity.

Note: BMI is a diagnostic instrument for individuals, but it does not diagnose body fatness or health. A trained health care provider should conduct the appropriate evaluations to determine the health status and hazards of an individual. If you have concerns about your BMI, consult with your doctor.

See the following table for an example.

Adult Body Mass Index (BMI)
Height	Weight Range	BMI	Considered
5′ 9″	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	Obesity
	271 lbs or more	40 or higher	Class 3 Obesity

BMI is moderately correlated with direct measures of body fat obtained from skinfold thickness measurements, bioelectrical impedance, submerged weighing, dual energy x-ray absorptiometry (DXA), and other techniques 1,2,3. In addition, the BMI appears to have a strong correlation with a variety of negative health outcomes, consistent with these more direct measures of body fatness 4,5,6,7,8,9.

For More Information

Body Mass Index interpretation and tools
Child and Teen BMI Percentile Calculator
Defining Childhood Obesity

References

1. Quetelet’s index (W/H2) as a measure of fatness. 1. Garrow, J.S., and J. Webster, 1985. Int. J. Obes., 9(2), pp.147–153.

2. Freedman, D.S., Horlick, M. & Berenson, G.S., 2013. A comparison of the Slaughter skinfold-thickness equations and the BMI for predicting body fatness and cardiovascular disease risk factor concentrations in children. American Journal of Clinical Nutrition, 98(6), 1417–24.

3. Body fat throughout childhood in 2647 healthy Danish children: agreement of BMI, waist circumference, and skinfolds with dual X-ray absorptiometry. Eur. J. Clin. Nutr., 68(6), pp.664–70.

4. Steinberger, J. et al., 2005. Body fatness measurements by BMI and skinfolds versus dual energy X-ray absorptiometry in adolescents and their relationship to cardiovascular risk factors. Int. J. Obes., 29(11), pp.1346–1352.

5. Sun, Q. et al., 2010. A comparison of dual-energy x-ray absorptiometric and anthropometric measures of adiposity in terms of adiposity-related biological factors. Am. J. Epidemiol., 172(12), pp.1442–1454.

6. Lawlor, D.A. et al., 2010. Prospective cohort study of the association between general and central adiposity in childhood, and changes in these, and cardiovascular risk factors in adolescence. BMJ, 341, p.c6224.

7. Estimates of excess mortality associated with body mass index and other anthropometric variables, by K.M. Flegal and B.I. Graubard, 2009. American Journal of Clinical Nutrition, 89(4), 1213–1219.