Accessible Search Form           Advanced Search


How Are Overweight and Obesity Diagnosed?

The most common way to find out whether you're overweight or obese is to figure out your body mass index (BMI). BMI is an estimate of body fat, and it's a good gauge of your risk for diseases that occur with more body fat.

BMI is calculated from your height and weight. You can use the chart below or the National Heart, Lung, and Blood Institute's (NHLBI's) online BMI calculator to figure out your BMI. Or, you health care provider can measure your BMI.

Body Mass Index for Adults

Use this table to learn your BMI. First, find your height on the far left column. Next, move across the row to find your weight. Weight is measured with underwear but no shoes.

Once you've found your weight, move to the very top of that column. This number is your BMI.


This table offers a sample of BMI measurements. If you don't see your height and/or weight listed on this table, go the NHLBI's complete Body Mass Index Table.

What Does Body Mass Index Mean?

18.5–24.9Normal weight
40.0 and aboveExtreme obesity

Although BMI can be used for most men and women, it does have some limits. It may overestimate body fat in athletes and others who have a muscular build. BMI also may underestimate body fat in older people and others who have lost muscle.

Body Mass Index for Children and Teens

Overweight are obesity are defined differently for children and teens than for adults. Children are still growing, and boys and girls mature at different rates.

BMIs for children and teens compare their heights and weights against growth charts that take age and sex into account. This is called BMI-for-age percentile. A child or teen's BMI-for-age percentile shows how his or her BMI compares with other boys and girls of the same age.

For more information about BMI-for-age and growth charts for children, go to the Centers for Disease Control and Prevention's BMI-for-age calculator.

What Does the BMI-for-Age Percentile Mean?

BMI-for-Age Percentile 
Less than 5th percentileUnderweight
5th percentile to less than the 85th percentileHealthy weight
85th percentile to less than the 95th percentileOverweight
95th percentile or greaterObese

Waist Circumference

Health care professionals also may take your waist measurement. This helps screen for the possible health risks related to overweight and obesity in adults.

If you have abdominal obesity and most of your fat is around your waist rather than at your hips, you're at increased risk for coronary heart disease and type 2 diabetes. The risk goes up with a waist size that's greater than 35 inches for women or greater than 40 inches for men.

You also can measure your waist size. To do so correctly, stand and place a tape measure around your middle, just above your hipbones. Measure your waist just after you breathe out.

Specialists Involved

A primary care doctor (or pediatrician for children and teens) will assess your BMI, waist measurement, and overall health risk. If you're overweight or obese, or if you have a large waist size, your doctor should explain the health risks and find out whether you're interested and willing to lose weight.

If you are, you and your doctor can work together to create a treatment plan. The plan may include weight-loss goals and treatment options that are realistic for you.

Your doctor may send you to other health care specialists if you need expert care. These specialists may include:

  • An endocrinologist if you need to be treated for type 2 diabetes or a hormone problem, such as an underactive thyroid.
  • A registered dietitian or nutritionist to work with you on ways to change your eating habits.
  • An exercise physiologist or trainer to figure out your level of fitness and show you how to do physical activities suitable for you.
  • A bariatric surgeon if weight-loss surgery is an option for you.
  • A psychiatrist, psychologist, or clinical social worker to help treat depression or stress.
Rate This Content:

previous topic next topic

Featured Video

Obesity happens one pound at a time. So does prevention.

Overweight and Obesity Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Overweight and Obesity, visit

Overweight and Obesity in the News

November 8, 2013
NIH and the Children's Museum of Manhattan launch innovative program to help families create healthier futures
Through an innovative public-private partnership, the National Institutes of Health and the Children's Museum of Manhattan (CMOM) have created a new health educational curriculum — EatPlayGrow: Creative Activities for a Healthy Start — for children ages 2-5 and their parents

View all Overweight and Obesity Press Releases

NHLBI Research Featured in HBO Documentary Series on Obesity

Hear people talk about their challenges and successes reaching and maintaining a healthy weight on the HBO Documentary Films series, “The Weight of the Nation,” which premiered in May 2012.

The film series spotlights the science behind obesity and how it affects the health of the nation. Watch the series to learn how citizens, groups, and policymakers are working to make a difference in their communities. The films stream free on the HBO Web site.

To learn more about the film series and related public awareness campaign, including how to host a local screening go to

July 13, 2012 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.