DefinitionObesity classes split adult obesity into three BMI bands, class 1, class 2 and class 3, to describe how far above the obesity threshold a person's BMI is.
What it means
CDC categories for adults 20 and older:
- Class 1: BMI 30 to less than 35
- Class 2: BMI 35 to less than 40
- Class 3: BMI 40 or higher, sometimes called severe obesity
Health risks generally rise with each class, though BMI does not capture fat distribution, muscle or fitness. Two people in the same class can have very different health.
The classes show up in treatment rules. The NIDDK says adults with a BMI of 40 or higher, or 35 or higher with a serious weight-related condition, may qualify for bariatric surgery. Insurers may use classes in coverage criteria too.
The CDC reported that about 9.2% of US adults had severe obesity in 2017 to March 2020. For children and teens, severe obesity is defined using BMI percentiles instead.
Why it matters
Your obesity class can affect which treatments and coverage paths are open to you.