About 9.7% of American adults have severe (morbid) obesity, which translates to roughly 1 in 10 people aged 20 and older. That figure comes from the most recent national survey data, collected between August 2021 and August 2023 by the CDC’s National Center for Health Statistics. Among children and adolescents, the rate is 7.0%.
What Counts as Morbid Obesity
Morbid obesity, now more commonly called Class 3 or severe obesity in clinical settings, is defined as a body mass index (BMI) of 40 or higher. For context, a 5’9″ person would reach that threshold at roughly 270 pounds, and a 5’4″ person at about 235 pounds. The CDC subdivides obesity into three classes: Class 1 (BMI 30 to 34.9), Class 2 (BMI 35 to 39.9), and Class 3 (BMI 40 and above). Class 3 carries the highest risk of weight-related health complications and is the category most people mean when they search for “morbidly obese.”
Women Are Affected Nearly Twice as Often as Men
The gender gap in severe obesity is striking. Among American women, 12.1% meet the threshold, compared to 6.7% of men. That pattern holds across every adult age group. After adjusting for age differences in the population, the numbers shift only slightly: 12.6% for women and 6.8% for men.
The reasons behind this disparity are complex. Hormonal differences, particularly shifts during pregnancy and menopause, influence how and where the body stores fat. Women also face higher rates of certain conditions tied to weight gain, including polycystic ovary syndrome and thyroid disorders. Socioeconomic factors play a role too: women in lower-income households experience obesity at higher rates than men in the same income bracket.
Rates Vary Sharply by Race and Ethnicity
Severe obesity does not affect all racial and ethnic groups equally. Based on national survey data:
- Non-Hispanic Black adults: 13.8%, the highest rate of any group
- Non-Hispanic white adults: 9.3%
- Hispanic adults: 7.9%
- Non-Hispanic Asian adults: 2.0%, the lowest rate
These differences reflect a web of structural factors, including disparities in access to affordable healthy food, safe spaces for physical activity, healthcare, and the cumulative effects of chronic stress. They are population-level patterns, not individual inevitabilities.
Severe Obesity in Children
Among Americans aged 2 to 19, 7.0% have severe obesity, defined differently for children than for adults. Instead of a flat BMI cutoff, severe obesity in young people means a BMI at or above 120% of the 95th percentile for their age and sex. Another 15.1% of children and adolescents are overweight without meeting the obesity threshold, and 21.1% overall have obesity of any class.
Childhood severe obesity is particularly concerning because it tends to persist into adulthood. Children who reach this weight category face earlier onset of conditions typically associated with middle age, including high blood pressure, type 2 diabetes, fatty liver disease, and joint problems. The psychological toll is significant as well: bullying, social isolation, and depression are more common in children with severe obesity.
Health Risks at This Weight Category
At a BMI of 40 or above, the body is under considerable metabolic and mechanical stress. Type 2 diabetes risk climbs sharply, as excess fat tissue, particularly around the organs, interferes with the body’s ability to regulate blood sugar. High blood pressure is common because the heart has to work harder to pump blood through a larger body. Sleep apnea, where breathing repeatedly stops during sleep, affects a large share of people in this weight range because extra tissue around the airway can collapse during rest.
Joint pain accelerates as well. Every extra pound of body weight translates to roughly four pounds of additional force on the knees during walking. At the severe obesity threshold, that mechanical load can break down cartilage years or decades earlier than it otherwise would. The risk of certain cancers, including those of the colon, breast, kidney, and pancreas, also rises with increasing BMI.
Perhaps most importantly, severe obesity shortens life expectancy. Studies consistently show that people with a BMI above 40 lose, on average, several years of life compared to those at a healthy weight, with the effect growing more pronounced at higher BMIs.
How the Numbers Have Changed
Severe obesity was relatively rare in the United States just a few decades ago. In the early 2000s, roughly 5% of adults qualified. By 2017 to 2018, that figure had climbed to 9.2%. The most recent data, from 2021 to 2023, puts the age-adjusted rate at 9.7%. That trajectory means the prevalence of severe obesity has nearly doubled in about 20 years, growing faster than overall obesity rates during the same period.
This acceleration matters because Class 3 obesity is the most difficult to reverse through lifestyle changes alone and carries the steepest health consequences. It also places the greatest strain on the healthcare system, as people in this weight category use more medical resources on average and face higher rates of hospitalization. The recent arrival of a new class of weight-loss medications has introduced a potential shift in treatment options, though long-term population-level effects remain to be seen.