Having class 3 (severe) obesity may shorten your life span by up to 14 years. If you have severe obesity, reducing your weight can improve your life expectancy.

Obesity is a common health condition in the United States. The Centers for Disease Control and Prevention (CDC) defines obesity as a body mass index (BMI) of 30 or higher.

The rate of obesity in the United States was 41.9% from 2017–2020, with around 9% of people having class 3 obesity, according to the CDC.

Class 3 obesity means that an individual has a body mass index (BMI) of 40 or greater. Class 3 obesity increases the risk of health conditions like heart disease. It can also shorten life expectancy up to 14 years if not treated.

This article takes a closer look at life expectancy for people with class 3 obesity, along with its associated health risks and options for managing weight.

Understanding the three classes of obesity

According to the CDC, obesity can be subdivided into three categories based on BMI:

  • Class 1 obesity is a BMI of at least 30 but less than 35.
  • Class 2 obesity is a BMI of at least 35 but less than 40.
  • Class 3 obesity is a BMI of 40 or greater.

Read more about the different classes of obesity.

The CDC reports that as of 2020, the percentage of people with class 3 obesity in the United States was 9.2%. The rates of class 1 and 2 obesity, as well as class 3 obesity, were on the rise.

According to a 2014 analysis of 20 studies that included 9,564 people with class 3 obesity, class 3 obesity reduced life span by 6.5–13.7 years.

A 2017 study indicates that life expectancy for people with class 3 obesity may be shortened by as much as 20 years.

To help put this in perspective, this is similar to the difference in life expectancy between people who have never smoked and current smokers. The average life span of a person who smokes more than 20 cigarettes a day is 13 years shorter than someone who doesn’t smoke, according to a 2022 study.

Researchers in the 2017 study determined that the greater a person’s BMI with class 3 obesity, the higher the risk of death. The obesity-associated conditions with the greatest risk of death are cardiovascular disease and cancer.

Losing weight can help improve a person’s life expectancy.

The following approaches can treat class 3 obesity:

Oftentimes, a combination of treatments works best.

Lifestyle strategies

Prioritizing a nutrient-dense, balanced diet alongside regular physical activity are important treatment options for class 3 obesity.

Working with a dietitian, personal trainer, or physical therapist may be beneficial as you make any changes your doctor suggests.

Behavioral therapy

Therapy can also help you make lifestyle changes to lose weight. Joining a weight loss support group may help supplement any individual therapy. Your doctor can suggest a local support group, or you can join a virtual group online.

Medications

In addition to lifestyle strategies, your doctor may prescribe medications to help reduce your appetite and lose weight.

These medications can come with a variety of side effects, so it’s important to discuss what to expect with your doctor before you begin using these drugs.

Taking medications to treat any underlying health conditions may also help with losing weight.

Surgery

Weight loss surgery may be helpful in treating severe obesity, especially when used in combination with other treatments.

If you think you might be a good candidate for weight loss surgery, discuss it with your doctor. They can advise you on your surgical options.

Obesity is a common health condition in the United States. Doctors now divide obesity into three classes based on severity:

  • Class 1 obesity is a BMI of at least 30 but less than 35.
  • Class 2 obesity is a BMI of at least 35 but less than 40.
  • Class 3 obesity is a BMI of 40 or greater.

Class 3 obesity is also sometimes referred to as severe obesity.

When untreated, class 3 obesity may shorten your life span by up to 14 years. Lifestyle strategies, therapy, medications, and surgery can help you reduce your weight, improve your quality of life, and extend your life span.

Talk with a doctor about how to get started. They can provide recommendations for which weight reduction options might work best for you.