The Healthier You
Jennifer Bianchi DTR
ABOUT BMI FOR ADULTS
What is BMI?
Body Mass Index (BMI) is a number calculated from a person’s weight and height. BMI is a reliable indicator of body fatness for people.
How is BMI used?
BMI is used as a screening tool to identify possible weight problems for adults. However, BMI is not a diagnostic tool. For example, a person may have a high BMI. However, to determine if excess weight is a health risk, a healthcare provider would need to perform further assessments. These assessments might include skinfold thickness measurements, evaluations of diet, physical activity, family history, and other appropriate health screenings.
What is another way to measure obesity?
Waist circumference; 40 inch waist circumference or more for men and 35 inches or more for women indicates obesity. Abdominal fat is a predictor of risk for obesity-related diseases.
Is BMI interpreted the same way for children and teens as it is for adults?
Although the BMI number is calculated the same way for children and adults, the criteria used to interpret the meaning of the BMI number for children and teens are different from those used for adults. For children and teens, BMI age- and sex-specific percentiles are used for two reasons:
- The amount of body fat changes with age.
- The amount of body fat differs between girls and boys.
For more information about interpretation for children and teens, visit
The standard weight status categories associated with BMI ranges for adults are shown in the following table.
|
BMI
|
Weight Status
|
|
Below 18.5
|
Underweight
|
|
18.5 – 24.9
|
Normal
|
|
25.0 – 29.9
|
Overweight
|
|
30.0 and Above
|
Obese
|
For example, here are the weight ranges, the corresponding BMI ranges, and the weight status categories for a sample height.
|
Height
|
Weight Range
|
BMI
|
Weight Status
|
|
5’ 9”
|
124 lbs or less
|
Below 18.5
|
Underweight
|
|
125 lbs to 168 lbs
|
18.5 to 24.9
|
Normal
|
|
|
169 lbs to 202 lbs
|
25.0 to 29.9
|
Overweight
|
|
|
203 lbs or more
|
30 or higher
|
Obese
|
How reliable is BMI as an indicator of body fatness?
The correlation between the BMI number and body fatness is fairly strong; however the correlation varies by sex, race, and age. These variations include the following examples: 3, 4
- At the same BMI, women tend to have more body fat than men.
- At the same BMI, older people, on average, tend to have more body fat than younger adults.
- Highly trained athletes may have a high BMI because of increased muscularity rather than increased body fatness.
If an athlete or other person with a lot of muscle has a BMI over 25, is that person still considered to be overweight?
According to the BMI weight status categories, anyone with a BMI over 25 would be classified as overweight and anyone with a BMI over 30 would be classified as obese.
It is important to remember, however, that BMI is not a direct measure of body fatness and that BMI is calculated from an individual’s weight which includes both muscle and fat. As a result, some individuals may have a high BMI but not have a high percentage of body fat. For example, highly trained athletes may have a high BMI because of increased muscularity rather than increased body fatness.
It is also important to remember that weight is only one factor related to risk for disease. If you have questions or concerns about the appropriateness of your weight, you should discuss them with your healthcare provider.
What are the health consequences of overweight and obesity for adults?
- Hypertension
- Dyslipidemia (for example, high LDL cholesterol, low HDL cholesterol, or high levels of triglycerides)
- Type 2 diabetes
- Coronary heart disease
- Stroke
- Gallbladder disease
- Osteoarthritis
- Sleep apnea and respiratory problems
- Some cancers (endometrial, breast, and colon)
.
References
1Mei Z, Grummer-Strawn LM, Pietrobelli A, Goulding A, Goran MI, Dietz WH. Validity of body mass index compared with other body-composition screening indexes for the assessment of body fatness in children and adolescents. American Journal of Clinical Nutrition 2002;7597–985.
2Garrow JS and Webster J. Quetelet's index (W/H2) as a measure of fatness. International Journal of Obesity 1985;9:147–153.
3Prentice AM and Jebb SA. Beyond Body Mass Index. Obesity Reviews. 2001 August; 2(3): 141–7.
4Gallagher D, et al. How useful is BMI for comparison of body fatness across age, sex and ethnic groups? American Journal of Epidemiology 1996;143:228–239.
5World Health Organization. Physical status: The use and interpretation of anthropometry. Geneva, Switzerland: World Health Organization 1995. WHO Technical Report Series.
