Your body is made up of water, fat, protein, carbohydrate and various vitamins and minerals. If you have too much fat — especially if a lot of it is at your waist — you're at higher risk for such health problems as high blood pressure, high blood cholesterol and diabetes. That increases your risk for heart disease and stroke.
Obesity is now recognized as a major, independent risk factor for heart disease. If you're overweight or obese, you can reduce your risk for heart disease by successfully losing weight and keeping it off.
Waist circumference and body mass index (BMI) are indirect ways to assess your body composition. Waist-to-hip ratio (WHR) is another index of body fat distribution. However, WHR is less accurate than BMI or waist circumference and is no longer recommended.
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 40 inches if you're a man and less than 35 inches if you're a woman.
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). In 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 NIH guidelines) — 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 thickness or more direct methods of measuring body fat may be more useful measures.
Use a weight scale on a hard, flat, uncarpeted surface. Wear very little clothing and no shoes.
Weigh yourself to the nearest pound.
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.
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.
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, multiply your weight in pounds by 703, divide by your height in inches, then divide again by your height in inches. (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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