A BMI between 18.5 and 24.9 is considered healthy for women over age 20 according to the Centers for Disease Control and Prevention. BMI ranges are the same for men and women over age 20, but they differ by age and sex for children and teenagers.Continue Reading
As of 2014, a BMI below 18.5 is classified as underweight in adults over age 20 of both sexes, explains the CDC. A BMI from 25 to 29.9 classifies an adult as overweight, while a BMI of over 30 signals clinical obesity.
The calculation of someone's BMI is accomplished by dividing weight in pounds by height in inches squared and then multiplying the result by 703, according to the CDC. If a woman is 68 inches tall and weighs 175 pounds, the calculation is (175 / 68^2) x 703, which results in a BMI of about 26.6. This calculation is the same in people of all ages, although the ranges of BMIs considered healthy vary for those under age 20.
While there is a strong correlation between BMI and body-fat level in most of the population, the CDC notes that highly active individuals can have BMIs in the overweight range while not having an unhealthy amount of body fat because they have a higher muscle mass. However, the majority of people in the obese BMI category have a high body-fat percentage.Learn more about Medical Ranges & Levels