BMI - Body Mass Index

Learn all about the Body Mass Index on this page. For a BMI calculator, charts, formulas and more, visit our BMI Charts, Formula and Calculator page.

What Is BMI?

BMI stands for Body Mass Index, and it measures body fat in relation to height and weight. The BMI is an inexpensive way to screen for and identify potential weight problems for adults. For both male and female adults, the BMI furnishes a fairly reliable indication of total body fat, and it correlates to more direct measures of body fat such as dual energy x-ray absorptiometry (DXA) and underwater weighing.

How Is BMI Calculated?

To calculate your BMI, you can use a BMI calculator that allows you to enter your height and weight. This calculator will return you a number representing your BMI. The formula used is your weight (in kilograms) divided by your height squared (in meters) or your weight (in pounds) divided by your height squared (in inches) multiplied by 703.

How Do You Interpret BMI Results?

BMI is interpreted the same for all adults. For children and teenagers, however, the BMI must be interpreted based on age and sex as well. The normal BMI range for an adult is 18.5 to 24.9. If your BMI is less than 18.5, you are considered underweight. If your BMI is in the 25-29.9 range, then you are overweight. A BMI of 30 or above indicates obesity and may be subject for concern.

What Are The Limitations of Using the BMI?

The BMI does not take into account muscle mass, and consequently it may overestimate total body fat for athletes, weight lifters, or someone with a particularly muscular build. Those who have lost muscle mass, such as older people, may find that the BMI underestimates their total body fat. Although the BMI makes no distinction between the sexes for adults, women tend to have more body fat than men do at the same BMI.

What Should I Be Concerned About If I Have a High BMI?

A high BMI could mean increased risk of disease. Keep in mind, however, that the BMI is just one indicator of risk. You will also want to take into account your waist circumference and other risk factors. It is best to consult a physician before embarking upon any weight loss plan.

For someone with a BMI of 40 or above, the disease risk is "extremely high" when compared to someone of a normal weight and waist circumference. A BMI of 35-40 generally means a "very high" risk, and a BMI of 30-35 a "high" risk. Overweight people with a BMI of 25-29.9 experience an "increased" risk of disease. Obesity-associated diseases include Type 2 Diabetes, heart disease, high blood cholesterol, stroke, and certain cancers.

Weight loss is recommended if your BMI falls in the obese range or if it falls into the overweight range and you also have two or more risk factors such as high LDL-cholesterol, low-HDL cholesterol, premature heart disease, high blood glucose (sugar), smoking, a sedentary lifestyle, or high triglycerides. You can lower your risk of developing obesity-related diseases even with a weight loss as small as 10 percent of your current weight.

Learn More:

BMI Calculators - Standard and metric calculators, charts and formulas.

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