Obesity is often defined as having a body mass index (BMI) of 30 or higher. However, there are actually three different classes of obesity, and they’re organized according to severity.
Obesity is a chronic medical condition that’s characterized by having excess body fat. Having obesity can increase your chance of several health conditions, including heart disease, stroke, and diabetes.
The prevalence of obesity is increasing in the United States. Data collected between 2017 and 2020 estimates that
While experts still categorize obesity based on severity, the medical community is moving away from terms like “morbid obesity.” Instead, obesity is divided into three different classes according to its severity as well as your BMI measurements.
Keep reading to learn more about these three classes.
The table below shows the
|30 to less than 35
|35 to less than 40
|40 or higher
Class 3 obesity is the most severe class of obesity. As such, you may also hear experts refer to class 3 obesity as “severe” or “extreme” obesity.
The prevalence of each class of obesity generally decreases as severity increases. For example, a
- A total of 20.17% of participants had class 1 obesity.
- A total of 8.98% of participants had class 2 obesity.
- A total of 6.32% of participants had class 3 obesity.
BMI is used as a measure of the different obesity classes. It estimates your body fat based on your height and weight.
Experts calculate BMI by dividing your weight in kilograms by the square of your height in meters. There are many BMI calculators available online that can do this for you, including one by the
A note on BMI measurements
BMI is used as a screening tool and isn’t a definitive measure of your actual level of body fat or your overall health. Other factors, such as the distribution of fat, may also be important.
For example, measurements like waist circumference and waist-to-hip ratio take abdominal fat into account. Abdominal, or visceral, fat is associated with a variety of health risks, including in people with
Studies have investigated the effects of the different classes of obesity on various aspects of health and healthcare, including:
- the chance of death (mortality)
- the chance of developing additional health conditions (comorbidities)
- the cost of healthcare
Increased chance of mortality
Obesity is generally
Mortality risk is particularly high for class 3 obesity. A
Increased chance of comorbidities
- heart and blood vessel conditions
- type 2 diabetes
- nonalcoholic fatty liver disease
- sleep apnea
When two or more conditions exist at the same time, they’re called comorbidities. One
Increased healthcare costs
Obesity and its complications can lead to an increase in doctor’s visits and associated medical costs. Overall, researchers have estimated that obesity is associated with
- Having class 1 obesity increased expenditures by 68%.
- Having class 2 obesity increased expenditures by 120%.
- Having class 3 obesity increased expenditures by 233.6%.
Obesity is divided into three different classes. Each class is made up of a specific BMI range.
The different classes of obesity are based on severity. Class 1 is the least severe class, while class 3 is the most severe.
Obesity is associated with an increased chance of death and comorbidities as well as higher medical expenses. These effects tend to be larger as obesity class increases.
If you’ve had a diagnosis of obesity, talk with your doctor about ways to manage your weight. They can recommend weight management strategies that are safe and appropriate for your situation.