About 40% of American adults have obesity. The most recent federal data, collected between August 2021 and August 2023, puts the figure at 40.3%, with no significant difference between men and women. That translates to roughly 100 million adults.
How Obesity Is Defined
Obesity is measured using BMI, a ratio of weight to height. A BMI of 30 or higher qualifies as obese. Within that range, there are three classes: Class 1 (BMI 30 to 34.9), Class 2 (BMI 35 to 39.9), and Class 3 (BMI 40 or above). For reference, a 5’9″ person crosses into obesity at around 203 pounds.
Severe obesity, meaning Class 3, affects 9.7% of U.S. adults. That number has been climbing even as the overall obesity rate has leveled off. Between 2013 and 2023, the overall rate didn’t change significantly, but severe obesity rose from 7.7% to 9.7%.
Childhood Obesity
Nearly one in five young people in the U.S. has obesity. The prevalence among children and adolescents aged 2 to 19 is 19.7%, affecting approximately 14.7 million kids. That rate has also risen sharply over the past two decades, though not as steeply as the adult numbers.
Rates by Race and Ethnicity
Obesity rates vary substantially across racial and ethnic groups. Non-Hispanic Black adults have the highest prevalence at 49.6%, followed by Hispanic adults at 44.8% and non-Hispanic white adults at 42.2%. Non-Hispanic Asian adults have the lowest rate at 17.4%. These gaps reflect longstanding disparities in food access, neighborhood environments, and economic opportunity rather than biological differences between groups.
Where Obesity Rates Are Highest
Geography plays a role too. Seventeen states, along with Puerto Rico and the U.S. Virgin Islands, have obesity rates between 35% and 40%. Mississippi and West Virginia top the list, with rates at or above 40%. Southern and Midwestern states consistently rank higher than coastal states, a pattern that has held for over a decade.
How the Rate Has Changed Over Time
The U.S. obesity rate climbed steadily from 1999 through 2018, then plateaued. That leveling off sounds like good news, but it means the rate stabilized at a historically high point rather than declining. The plateau also masks the continued rise in severe obesity, which suggests the population isn’t just staying heavy but that the heaviest Americans are getting heavier.
A projection from researchers at Harvard’s school of public health estimates that about half of U.S. adults will have obesity by 2030. The same study predicts that more than half the population will be obese in 29 states, with some states approaching 60%. Every state is expected to exceed 35%. Roughly one in four adults is projected to have severe obesity by that point.
The Financial Cost
Obesity-related medical spending reached nearly $173 billion in 2019. On an individual level, people with obesity spend about $1,861 more per year on healthcare than people at a normal weight. Those costs come from higher rates of type 2 diabetes, heart disease, joint problems, sleep apnea, and several types of cancer, all conditions strongly linked to excess body fat.
What the Numbers Don’t Capture
BMI is a blunt tool. It doesn’t distinguish between muscle and fat, doesn’t account for where fat is stored, and can misclassify muscular people as obese while missing metabolically unhealthy people at lower weights. Still, at a population level, BMI tracks reliably with health outcomes, which is why public health agencies continue to use it as their primary measure. The 40.3% figure is the best snapshot available of how widespread obesity is in the U.S., even if it doesn’t tell the full story for any single person.