Body Mass Index

If you have too much fat — especially if a lot of it is located at your waist — you're at higher risk for health problems, including obesity, high blood pressure, high blood cholesterol, diabetes, and consequently heart disease and stroke. Waist circumference and body mass index (BMI) are indirect ways to assess your body composition.

What is the waist circumference?
What is body mass index?
How do you find your BMI risk level?


What is the waist circumference?

Waist circumference is the distance around your natural waist (just above the navel). If your BMI is greater than or equal to 25 kg/m2, your goal for waist circumference is less than or equal to 40 inches if you are a man and less than or equal to 35 inches if you are a woman.

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What is body mass index?

Body mass index assesses your body weight relative to height. It's a useful, indirect measure of body composition because it correlates highly with body fat in most people. Weight in kilograms is divided by height in meters squared (kg/m2). Based upon studies by the National Center for Health Statistics,

  • BMI values less than 18.5 are considered underweight.
  • BMI values from 18.5 to 24.9 are healthy.
  • Overweight is defined as a body mass index of 25.0 to less than 30.0. A BMI of about 25 kg/m2 corresponds to about 10 percent over ideal body weight. People with BMIs in this range have an increased risk of heart and blood vessel disease.
  • Obesity is defined as a BMI of 30.0 or greater (based on 1998 NIH guidelines), or about 30 pounds or more overweight. People with BMIs of 30 or more are at higher risk of cardiovascular disease.
  • Extreme obesity is defined as a BMI of 40 or greater.

Some well-trained people with dense muscle mass may have a high BMI score but very little body fat. For them the waist circumference, the skinfold or fatfold measurements, or more direct methods of measuring body fat may be more useful.

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How do you find your BMI risk level?

  1. Use a weight scale on a hard, flat, uncarpeted surface. Wear very little clothing and no shoes.

  2. Weigh yourself to the nearest pound.

  3. With your eyes facing forward and your heels together, stand very straight against a wall. Your buttocks, shoulders and the back of your head should be touching the wall.

  4. Mark your height at the highest point of your head. Then measure your height in feet and inches to the nearest 1/4 inch. Also figure your height in inches only.

  5. Find your height in feet and inches in the first column of the Body Mass Index Risk Levels table. The ranges of weight that correspond to minimal risk, moderate risk (overweight) and high risk (obese) are shown in the three columns for each height.

Height Minimal risk
(BMI under 25)		 Moderate risk
(BMI 25-29.9)
Overweight		 High risk
(BMI 30 and above)
Obese
4'10" 118 lbs. or less 119-142 lbs. 143 lbs. or more
4'11" 123 or less 124-147 148 or more
5'0" 127 or less 128-152 153 or more
5'1" 131 or less 132-157 158 or more
5'2" 135 or less 136-163 164 or more
5'3" 140 or less 141-168 169 or more
5'4" 144 or less 145-173 174 or more
5'5" 149 or less 150-179 180 or more
5'6" 154 or less 155-185 186 or more
5'7" 158 or less 159-190 191 or more
5'8" 163 or less 164-196 197 or more
5'9" 168 or less 169-202 203 or more
5'10" 173 or less 174-208 209 or more
5'11" 178 or less 179-214 215 or more
6'0" 183 or less 184-220 221 or more
6'1" 188 or less 189-226 227 or more
6'2" 193 or less 194-232 233 or more
6'3" 199 or less 200-239 240 or more
6'4" 204 or less 205-245 246 or more

To calculate your exact BMI value*:

  1. Multiply your weight in pounds by 703
  2. Divide by your height in inches (5 feet = 60 inches),
  3. Divide again by your height in inches

Example:
If you were 5´7″ and weighed 150 pounds, your BMI calculation would look like this:
150 x 703 = 105,450
105,450 ÷ 67 = 1,573.88
1,573.88 ÷ 67 = 23.5
Your BMI would be 23.5

* Adapted from Obesity Education Initiative: Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults,National Institutes of Health, National Heart, Lung, and Blood Institute, Obesity Research 1998; 6 Suppl 2: 51S-209S

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