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Body Mass Index Calculator

bmi illustration
8 women with the same BMI but
differing weight distribution

By Angie Best-Boss, Contributing Writer

Body mass index (BMI) is a measure of body fat based on height and weight that applies to both adult men and women. As the Centers for Disease Control explains, 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.

BMI Categories:

  • Underweight = 18.5
  • Normal weight = 18.5-24.9
  • Overweight = 25-29.9
  • Obesity = BMI of 30 or greater

The score is valid for both men and women but it does have some limits. The limits are:

  • It may overestimate body fat in athletes and others who have a muscular build.
  • It may underestimate body fat in older persons and others who have lost muscle mass.
  • Heart disease, diabetes and high blood pressure are all linked to being overweight. A BMI of 30 and over increases the risk of death from any cause by 50 to 150 percent, according to some estimates. According to health experts, people who are overweight but have no other health risk factors (such as high cholesterol or high blood pressure) should eat healthier and exercise to keep from gaining additional weight. For people who are overweight and also have health risks, they recommend trying to actively lose weight.
  • To determine your BMI, go to the National Heart, Lung and Blood Institute.

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