Person walking

What is super morbidly obese (severe obesity)?

By Ruben J. Rucoba, MD Mar 21, 2024 • 4 min

Approximately 4 in every 10 adults in the U.S. are obese, according to the Centers for Disease Control and Prevention (CDC). There are several different levels of obesity, and the risk of certain health problems can rise as the level of obesity increases, so it can be helpful to know about these obesity classifications. Let's learn more about the different subgroups of obesity and their health risks, including what it means to be super morbidly obese (now referred to as severely obese).

Classifications of obesity

Obesity in adults has been defined and divided into subgroups by the National Institutes of Health (NIH) using body mass index (BMI). The BMI is calculated by dividing the body weight, in kilograms, by the height, in meters, squared. For example, a person with a body weight of 80 kg and 1.76 m height has a BMI of 25.8 kg/m² (calculated from 80 divided by 1.76 and divided again by 1.76).

BMI is only a rough estimate of obesity, but it's a quick way to get an idea of a person's weight compared to height. The NIH groups people by BMI into different ranges:

  • Underweight: BMI under 18.5
  • Normal weight: BMI of 18.5–24.9
  • Overweight: BMI of 25.0–29.9
  • Obesity Class I (low-risk obesity): BMI of 30.0–34.9
  • Obesity Class II (moderate-risk obesity): BMI of 35.0–39.9
  • Obesity Class III (high-risk obesity, formerly referred to as morbid obesity): BMI of 40.0 or higher

Class III obesity is sometimes referred to as “severe” obesity, with more risk for other health conditions.

How does severe obesity differ from the other types of obesity?

A person who has severe obesity has a BMI of 40 or higher, nearly twice the BMI level of someone who is classified as overweight. A BMI of 30 or higher is considered obese. Obesity is often further divided into three categories — Class I, Class II and Class III — with Class III including all BMI numbers of 40 or greater. 

Studies have demonstrated that increasing levels of obesity put people at greater risk of negative health effects, such as:

  • Type 2 diabetes
  • Obesity hypoventilation syndrome (a dangerous condition involving disordered breathing that leads to too much carbon dioxide and too little oxygen in the blood) 
  • Complications during pregnancy, including  gestational diabetes and preeclampsia
  • Impaired healing of wounds
  • High blood pressure (hypertension)
  • Cancer
  • Heart disease
  • Inflammatory conditions, such as gout
  • Infertility in women
  • Depression
  • Digestive diseases, such as gallbladder disease and gastric reflux 
  • Musculoskeletal conditions, including osteoarthritis

What treatment is there for severe obesity?

For people with severe obesity, the treatment plan is usually multifaceted. The various treatments available include healthy eating plans, regular physical activity, weight management programs, behavior modification, bariatric surgery, medications and weight loss devices.

One example of a weight loss device is a gastric balloon system in which balloons are inserted into the stomach to make you feel fuller and eat less.

We've seen how the different levels of obesity can affect health. The good news is there are many lifestyle changes and treatments that can be implemented. If you're worried about possibly being obese and having trouble managing your weight, talk to your healthcare provider about ways to reduce your waistline and enjoy a healthier life.

Clinically reviewed and updated by Julie McDaniel, MSN, RN, CRNI, March 2024.