Oct. 3, 2024—You might check your body mass index (BMI) if you're wondering whether your weight is healthy. However, it doesn't tell the full story. Your waist size is just as important.
Experts at the American Medical Association (AMA) now say both BMI and waist size are needed to determine whether someone is at a healthy weight and whether they're at risk for certain health problems.
Here's what you need to know about both measurements—and why it may be time to pull out the measuring tape.
The limitations of BMI
BMI is a widely used method for estimating whether someone is at a healthy weight for their height. It's based on a person's weight and height, and it can provide some useful information. (If you're curious about yours, you can calculate it using this tool.)
But it has its drawbacks, notes the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). For one, BMI doesn't directly measure body fat. Someone with a high BMI might not actually be at risk if their body is muscular. Also, factors like ethnicity and age can influence BMI's accuracy. Older adults might have a misleading BMI score, for instance. That's because they tend to lose bone and muscle and gain body fat as they age.
So BMI shouldn't be used alone to assess a person's weight-related health risks, say the AMA and the NIDDK.
Why waist size matters
Measuring your waist is a simple way to tell how much fat you carry around your midsection. That's important, since higher levels of abdominal fat are linked to an increased risk for serious health problems, the Centers for Disease Control and Prevention (CDC) notes. That's true even if a person has a healthy BMI.
Having a too-large waist may raise your risk for:
- Heart disease.
- Type 2 diabetes.
- Stroke.
What's a healthy waist size?
These guidelines from CDC and other experts can help you know if your waist size puts you at risk for obesity-related health issues. For women, 35 inches or less is considered healthy. For men, 40 inches or less is the recommended healthy range.
You can find out your waist size at home. To get an accurate measurement:
- Stand up straight and place a tape measure around your midsection, right above your hip bones.
- Breathe in. Make sure the tape is snug but not tight. It should lie flat against your skin.
- Exhale and measure your waist just after you breathe out.
If you have concerns about your BMI or your waist size, talk with your doctor. They can assess your weight and, if needed, help you devise a plan to improve your weight and health.
Sources
- American Heart Association. "Too Much Belly Fat, Even for People With a Healthy BMI, Raises Heart Risks." https://www.heart.org/en/news/2021/04/22/too-much-belly-fat-even-for-people-with-a-healthy-bmi-raises-heart-risks.
- American Medical Association. "AMA: Use of BMI Alone Is an Imperfect Clinical Measure." https://www.ama-assn.org/delivering-care/public-health/ama-use-bmi-alone-imperfect-clinical-measure.
- Centers for Disease Control and Prevention. "Healthy Weight." https://www.cdc.gov/diabetes/living-with/healthy-weight.html.
- National Institute of Diabetes and Digestive and Kidney Diseases. "Am I at a Healthy Weight?" https://www.niddk.nih.gov/health-information/weight-management/adult-overweight-obesity/am-i-healthy-weight.