About 70% of US adults fall into the overweight or obese category when measured by body mass index (BMI), with roughly 42% meeting the obesity threshold (BMI 30 or higher) and another 30% sitting in the overweight range (BMI 25 to 29.9). Behind that round figure sits a sharper picture: nearly 1 in 10 adults qualifies as severely obese (BMI 40 or higher), a subset that behaves very differently in the data.
The percentages shift noticeably by age, sex, race, region, and education.
This detailed guide unpacks the latest U.S. obesity and overweight data, walking through how BMI categories are defined, where the percentages come from, and how the picture has shifted across three decades.
The Headline Number and What It Actually Covers
The 70% figure combines two distinct BMI bands: overweight and obese, and treating them as one block hides important differences in health risk, intervention, and trend trajectory. About 42% of US adults qualify as obese, meaning their BMI reaches 30 or higher. An additional 30% sit just below that line in the overweight band. The remaining 30% of adults fall into the normal-weight or underweight categories combined, a smaller slice than most people expect.
Breaking down the combined category
Obesity carries a higher disease burden than overweight, and the data reflects that. Roughly 9% of US adults qualify as severely obese (BMI 40+), a group that draws a disproportionate share of obesity-related healthcare spending. Separating severe obesity from the broader category matters because Class 3 (BMI 40+) behaves more like a chronic disease than a lifestyle factor, with elevated risks for type 2 diabetes, heart disease, and certain cancers.
| BMI Category | BMI Range | Approx. Share of US Adults |
|---|---|---|
| Underweight | Below 18.5 | ~2% |
| Normal weight | 18.5–24.9 | ~28% |
| Overweight | 25.0–29.9 | ~30% |
| Obesity (all classes) | 30.0+ | ~42% |
| Class 1 obesity | 30.0–34.9 | ~21% |
| Class 2 obesity | 35.0–39.9 | ~12% |
| Class 3 (severe) obesity | 40.0+ | ~9% |
Look closely at the underweight column and the math reconciles: roughly 30% in the normal-weight band plus 2% underweight plus the overweight and obese shares add up to the full US adult population. The “healthy weight range” is therefore narrower than most headlines suggest, and the “normal-weight” share has been shrinking for decades.
How BMI Defines These Categories in the First Place
BMI divides weight in kilograms by height in meters squared, then sorts the result into four adult bands: underweight, normal weight, overweight, and obese. The math is simple, which is why the World Health Organization adopted it in the 1990s as a screening tool for population-level weight surveillance. BMI was designed for groups, not for diagnosing individual patients.
The class system inside obesity
The obese category splits into three classes, and the labels map directly to risk tiers. Class 1 covers BMI 30 to 34.9, Class 2 covers 35 to 39.9, and Class 3 covers 40 or higher. Class 3 is also called severe obesity, and it carries the highest risk for weight-related complications.
Most national headlines report overall obesity (BMI 30+), but the class breakdown changes the picture: the 42% overall figure includes about 9% who fall into Class 3 alone.
Why BMI falls short for individuals
BMI does not distinguish muscle from fat, which limits its use as a personal verdict. A serious weightlifter and a sedentary person of the same height and weight can share a BMI, yet their body compositions have little in common. Ethnicity matters too: at the same BMI, Asian adults often show higher metabolic risk than White adults, which is why some guidelines suggest lower BMI cutoffs for certain populations.
BMI works as a population screen, then pairs with waist circumference, blood markers, or a clinician’s assessment for personal decisions.
Where These Numbers Come From and Why They Differ
Two federal surveys drive nearly every headline about American obesity, and they disagree by design. The National Health and Nutrition Examination Survey (NHANES), run by the CDC’s National Center for Health Statistics, measures height and weight during an in-person physical exam, so the data is objective. The Behavioral Risk Factor Surveillance System (BRFSS), a phone-based state survey, asks people to report their own height and weight, and people consistently overestimate height and underestimate weight on the phone.
Why self-reports undercount obesity
BRFSS surveys typically show obesity rates 5 to 8 percentage points lower than NHANES, even when sampling the same years, and the gap comes from social-desirability bias. Tallness gets rounded up, weight gets rounded down, and the resulting BMI drifts toward normal. Measured NHANES figures are treated as the gold standard for national obesity prevalence, a status confirmed in CDC methodology briefs and peer-reviewed comparisons.
Why CDC numbers move in two-year steps
NHANES releases obesity prevalence as two-year rolling averages rather than single-year figures, and averaging smooths out the year-to-year sampling noise that comes from rotating survey sites and varying participant counts. From 2019 to 2023, pandemic-era data collection paused in-person exams, which created gaps in the NHANES cycle and forced statisticians to rely on partial samples. Trend lines from those years carry wider confidence intervals, so single-percentage-point changes during that window deserve skepticism.
Those sampling gaps help explain why earlier trend lines looked smoother than the underlying reality probably was.
The Three-Decade Rise in American Obesity
US adult obesity prevalence trends tell a clear story of long, steep growth. In the early NHANES cycles (1988–1994), adult obesity sat near 23%. By the 2017–2020 cycle, it had climbed past 42%, with severe obesity (BMI 40+) growing even faster. The trajectory is not a straight line: growth flattened in the mid-2010s, ticked back up after 2020, and now sits at the highest measured level on record.
The targets the country has missed
Healthy People 2030, the federal blueprint for health goals, set a target of 36% adult obesity prevalence, and no US state has yet hit that target. The closest approaches come from a handful of Western states and the District of Columbia, where adult obesity rates hover in the mid-20% range. Many Southern and Midwestern states report adult obesity above 35%, putting them above the national target while still falling short of the highest state figures.
Who saw the steepest increases
The fastest growth has been concentrated in two groups: adults aged 40 to 59, and Black and Hispanic adults. Childhood obesity has climbed in parallel. Roughly 20% of US children and adolescents aged 6 to 19 now meet the obesity threshold (at or above the 95th BMI percentile for age and sex), triple the rate seen in the 1980s. Adolescent severe obesity (BMI at or above 120% of the 95th percentile) has grown even faster, doubling over the past decade.
How the Numbers Break Down by Demographics and Geography
National averages flatten real variation, and pulling the data apart exposes it. Demographics, geography, education, and income all fracture the 42% national obesity rate in the United States into a much wider spread. Those gaps help explain why a single number often feels too high or too low depending on where you live.
Differences by race and ethnicity
Obesity prevalence is highest among non-Hispanic Black adults (roughly 50%), followed by Hispanic adults (roughly 45%), and non-Hispanic White adults (roughly 42%), with non-Hispanic Asian adults consistently reporting the lowest rates (around 15%). The severe-obesity subset shows even wider gaps: non-Hispanic Black adults are nearly twice as likely as non-Hispanic White adults to have a BMI of 40 or higher.
Differences by region and state
State-level obesity varies by more than 20 percentage points, and the Midwest and South run hottest. West Virginia, Mississippi, Louisiana, and Oklahoma routinely post adult obesity rates above 40%. Colorado, Hawaii, Massachusetts, and California sit at the low end, in the mid-20% range. Regional differences track closely with income, food access, and built-environment factors such as walkability and recreational space.
Education and income patterns
Higher education and household income generally track with lower obesity prevalence, yet the relationship shifts across sex and ethnic groups. College-educated adults report lower obesity rates than those with a high-school diploma or less, and households earning above 350% of the federal poverty level show lower prevalence than those below 130%. Among non-Hispanic Black and Hispanic women, the income gradient flattens, meaning higher income does not consistently predict lower obesity in those groups.
How the US compares to other developed nations
American obesity statistics by year look especially heavy when stacked against peers. US adult obesity rates sit near the top among OECD countries, behind only a handful of small island nations with much smaller populations. Most Western European countries report adult obesity in the 15% to 25% range, roughly half the US figure. That contrast frames the 42% number as a population-scale outlier, not a typical developed-world outcome.
What These Figures Mean for Health and Where to Go Next
Excess weight is associated with higher risk for type 2 diabetes, heart disease, stroke, hypertension, sleep apnea, and several cancers (including endometrial, liver, kidney, and colorectal). The risk rises with BMI class: a person with Class 3 obesity faces substantially higher complications than someone in the overweight band. Obesity-related healthcare spending in the US runs into the hundreds of billions of dollars each year, which is why the trend matters far beyond personal health metrics.
Common health risks at elevated BMI
- Type 2 diabetes: Risk roughly doubles at BMI 30+ and climbs further at BMI 35+ and 40+, the CDC’s obesity-related health risks guidance notes.
- Hypertension and stroke: Excess weight raises blood pressure on average, and Class 2 and Class 3 obesity carry the steepest cardiovascular penalties.
- Heart disease: Higher BMI classes correlate with elevated coronary risk, even after adjusting for cholesterol and smoking.
- Sleep apnea: Prevalence climbs sharply at BMI 30+, with Class 3 obesity producing the most severe cases.
- Certain cancers: Endometrial, liver, kidney, and colorectal cancers all show elevated risk at BMI 30+.
- Severe COVID-19 outcomes: Hospitalization and death rates rose with BMI class during 2020–2022, contributing to sharper post-2020 prevalence reporting in some surveys.
Where to look for deeper or custom data
Treat the 70% figure as a starting point rather than an ending, and the right datasets will carry you further. NHANES gives measured, exam-based prevalence by age, sex, race, and BMI class, updated as new cycles release. BRFSS interactive tools let you pull state-level self-reported prevalence with custom filters for demographics and year. Together they cover nearly every public-facing question about how many Americans are obese, broken down the way your question needs.
The headline 70% is a snapshot, not a verdict. The data shows how common excess weight is, where it is rising fastest, and which groups carry the heaviest burden, so the next policy, program, or personal decision can be aimed at the right place.
The Bottom Line
The 70% figure is accurate, current, and just the surface of a more nuanced story, and the percentage of US adults overweight or obese keeps shifting under that surface. About 42% of US adults meet the threshold for obesity, with severe obesity now affecting 9% of the population, a group whose health risks and care costs shape national outcomes far more than the headline number suggests.
Adult obesity prevalence trends have flattened in some age groups and accelerated in others, especially among adults in midlife and among Black and Hispanic communities. Knowing the headline, the categories behind it, and the demographic gaps turns a single statistic into something you can actually use.
FAQ
What percentage of Americans are overweight or obese?
About 70% of US adults fall into the overweight or obese category combined. Roughly 30% sit in the overweight band (BMI 25 to 29.9), and about 42% meet the obesity threshold (BMI 30 or higher), based on the most recent NHANES data from the CDC.
What percentage of US adults are obese?
Roughly 42% of US adults meet the clinical threshold for obesity at BMI 30 or above, the most recent CDC NHANES figures show. Within that group, roughly 9% qualify as severely obese (BMI 40 or higher), a subset with notably higher health risks.
How is overweight and obesity measured?
Both categories use body mass index (BMI), a height-and-weight calculation that sorts adults into underweight, normal weight, overweight, and obese bands. Obesity is split into three classes based on BMI thresholds (30–34.9, 35–39.9, and 40+).
What is the obesity rate in the United States today?
Adult obesity across the United States has climbed past the 42% mark in the latest NHANES reporting cycles from the CDC. Severe obesity (BMI 40+) accounts for about 9% of that total.
What is the difference between overweight and obese?
Overweight covers BMI 25.0 to 29.9 and obesity covers BMI 30.0 or higher. Obesity is further divided into Class 1, Class 2, and Class 3 (severe), with each higher class carrying greater health risk.
How has the obesity rate changed over time?
US adult obesity has roughly tripled since the late 1980s, when prevalence sat near 23%. Growth slowed in the mid-2010s, ticked upward again after 2020, and now sits above 42% based on the most recent NHANES cycles.
