Body mass index

Jan 17, 2005 Viewed: 719

Alternative names
BMI

Information

A good way to assess your weight is to calculate your Body Mass Index (BMI). Your BMI estimates whether you are at a healthy weight. Being overweight puts strain on your heart and can lead to serious health problems. These problems include type 2 diabetes, heart disease, high blood pressure, sleep apnea, varicose veins, and other chronic conditions. More than 300,000 lives could be saved in the U.S. each year if everyone maintained a healthy weight!

HOW TO DETERMINE YOUR BMI

Your BMI estimates how much you should weigh, based on your height. Here are the steps to calculate it:

     
  • Multiply your weight in pounds by 703.  
  • Divide that answer by your height in inches.  
  • Divide that answer by your height in inches again.

For example, a woman who weighs 270 pounds and is 68 inches tall has a BMI of 41.0.

Use the chart below to see what category you fall into, and whether you need to be concerned about your weight.
BMI CATEGORY
Below 18.5 Underweight
18.5 - 24.9 Healthy
25.0 - 29.9 Overweight
30.0 - 39.9 Obese
Over 40 Morbidly Obese

EXCEPTIONS

BMI is not always an accurate way to determine whether you need to lose weight. Here are some exceptions:

     
  • Body builders: Because muscle weighs more than fat, people who are unusually muscular may have a high BMI.  
  • Elderly: In the elderly it is often better to have a BMI between 25 and 27, rather than under 25. If you are older than 65, for example, a slightly higher BMI may help protect you from osteoporosis.  
  • Children: While an alarming number of children are obese, do not use this BMI calculator for evaluating a child. Talk to your child’s doctor about what an appropriate weight is for his or her age.

OTHER METHODS

Doctors use a few different methods to determine whether you are overweight. Your doctor may also take your waist circumference and your waist-to-hip ratio into consideration.

In addition, a lot of other factors influence your health. These include diet, physical activity, smoking, blood pressure, cholesterol levels, and blood sugar levels.

Johns Hopkins patient information

Last revised: December 4, 2012
by Janet G. Derge, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.