How is class III obesity diagnosed?

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How is class III obesity diagnosed?

Healthcare providers diagnose class III obesity in part by determining a person’s body mass index (BMI). BMI is defined by the ratio of your height to your weight. Optimum BMI ranges from 20 to 25. An adult may be considered to have class III obesity if they meet one of the following criteria:

  • Are 100 pounds over the optimum body weight range for their sex and height.
  • Have a BMI of 40 or more.
  • Have a BMI of 35 or more and are experiencing obesity-related health conditions, such as high blood pressure or diabetes.

The BMI scale isn't always accurate for certain populations, and healthcare providers use a different scale to determine obesity in children.

Healthcare providers also use waist circumference measurements to help diagnose obesity.

In adults who aren't pregnant, a waist circumference over 35 inches for females or over 40 inches for males can help diagnose obesity. If you’re of South Asian or Central and South American descent, your provider may use smaller waist circumference values to diagnose obesity. People from these backgrounds often don’t show signs of a large waist circumference even though they may have unhealthy amounts of fat deep in their abdomens and may be diagnosed with obesity.

Providers can also estimate obesity by measuring skin thickness in the following areas of your body:

  • The back of your upper arms (triceps).
  • The front of your upper arms (biceps).
  • Under your shoulder blades (subscapular).
  • Above your hip bones (supra-iliac).

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