Waist Circumference & BMI

Being overweight or obese makes you more at risk for some health conditions, including heart disease, diabetes, high blood pressure, bladder disease, stroke and certain types of cancer. Both waist circumference and BMI, or body mass index, can be used to determine whether you are at a weight that increases your risk for these conditions.

Features

Measuring around your waist just above your belly button with a tape measure will give you your waist circumference. Your BMI is your weight, measured in kilograms, divided by your height, measured in meters, squared. You can also multiply your weight in pounds by 703, and then divide the result by your height in inches twice. However, you don't have to do this calculation yourself. BMI calculators and charts are readily available that let you plug in your height in inches and your weight in pounds to get your BMI.

Function

Although waist circumference and BMI don't measure the actual amount of body fat you have, they can more accurately predict disease risk than your weight alone. The World Health Organization and the National Institutes of Health have set cut-off points so these two measurements can be used to screen for disease risk. If your measurements are too high, you should lose weight and may undergo further testing to better determine your risk for obesity-related diseases.

Significance

Using these two measurements together can give a good idea of your risk for certain health conditions. If you have a BMI less than 18.5, you are considered underweight. A BMI between 18.5 and 24.9 is considered normal. If you have a BMI between 25 and 29.9, you are overweight and have an increased risk for obesity-related diseases if your waist circumference is less than 35 inches for women and 40 inches for men, and a high risk for these diseases if your waist circumference is larger than this. A BMI over 30 means you are considered obese, and are at a high or very high risk for these diseases, depending on your waist circumference.

Considerations

BMI measurements overestimate fat in athletes and people with a lot of muscle, and underestimate fat in elderly people who may have lost a lot of their muscle. This is why BMI is a screening tool, and not a diagnostic tool. Further screening and tests may be needed to determine your true level of disease risk.

Expert Insight

If your waist circumference and BMI are not in the normal levels, you should try to lose weight to improve your disease risk, especially if you have other risk factors for heart disease, according to the National Heart Lung and Blood Institute. These include high blood pressure, high LDL cholesterol, low HDL cholesterol, high blood sugar, high triglycerides, an inactive lifestyle, cigarette smoking and family members with heart disease.