Has America's obesity rate plateaued?

Just over 40% of Americans are obese based on their BMIs, and that number has been on the rise since the mid-1970s. But a few new statistics suggest that the obesity rate is now plateauing, or even declining.

Could this mean America has hit its heaviest weight on the scale? Experts aren't so sure.

The apparent plateau is short-term, the data incomplete and the share of people with severe obesity still rising. The childhood obesity rate also continues to rise. In addition, nutrition data suggests that Americans are still eating large amounts of ultraprocessed foods, which can fuel obesity.

For researchers, none of this news points to a change in the obesity trend.

"It's not a moment to relax," Niyati Parekh, a professor of public health nutrition at New York University, told Live Science.

The latest numbers

Obesity is defined as a body mass index (BMI) of 30 or higher, while "severe" obesity, also called Class III obesity, is defined as 40 or higher. This measure of body fat based on height and weight is imperfect for diagnosing individual health — for instance, someone with a very muscular build might qualify as overweight or obese despite having a healthy body composition. But it is used by public health officials to get a sense of how much of the population is overweight and obese.

Obesity, in turn, is linked to chronic health problems such as sleep apnea, cardiovascular disease, liver disease and diabetes.

The rate of obesity began rising in the U.S. across all groups starting in the late 1970s, according to data collected by the Centers for Disease Control and Prevention (CDC). In 1980, 13.4% of U.S. adults were obese. By 2008, 34.3% were. The latest data, collected between 2021 and 2023, shows that 40.3% of adults are obese.

That recent age-adjusted increase was not a statistically significant change compared with the decade prior, suggesting that the obesity rate is no longer rising. But the National Health and Nutrition Examination Survey (NHANES) from which these numbers emerge is limited, said Barry Popkin, a nutrition professor at the University of North Carolina whose work focuses on evaluating policy related to food labeling and obesity.

While the survey is a national sample, the North is surveyed in the summer and the South in the winter, making regional and seasonal comparisons impossible, Popkin said. More importantly, the survey compares the 2021-2023 numbers to a decade ago, which is only two data points.

"We have seen some short-term plateaus earlier at different points," Popkin said. There was a pause in the rise between 2009 and 2012, for example, that turned out to be a temporary bump in a continuing upward trajectory.

The most recent Gallup National Health and Well-Being Index, released Oct. 28, found an overall obesity rate of 37% in U.S. adults in 2025, down from a high in the same surveys of 39.9% in 2022. But there are questions about this data, too, said Justin Ryder, an associate professor of surgery and pediatrics at the Northwestern Feinberg School of Medicine and vice chair of research for the department of surgery at Lurie Children's Hospital in Chicago.

Gallup surveys about 5,000 adults each quarter, but it's not clear how many individuals in that sample have BMIs in the obese range, given that the participants are not chosen to be nationally representative by weight status.

Small sample sizes can skew the picture, Ryder said. Over a decade ago, he said, there was data suggesting the obesity rate was dropping in 2- to 5-year-old children. But that trend turned out to be based on only 700 children, and in the next year of data collection, the findings evaporated. Ryder told Live Science he was skeptical of the Gallup data for a similar reason.

"I don't believe it," he said.

The role of GLP-1s

In reporting the results of the survey, Gallup suggested that new medications that target the glucagon-like peptide 1 (GLP-1) receptor might be making an impact on America's obesity rate. These medications, known by brand names such as Ozempic and Zepbound, help regulate blood sugar levels and slow the emptying of the stomach, leading to weight loss.

In Gallup's nationally representative sample, 12.4% of adults reported currently using one of these GLP-1 drugs, up from 5.8% in February 2024. The biggest reductions in obesity rates in Gallup's numbers were in people ages 40 to 64, matching the highest uptake of GLP-1 medications.

Overall, though, it's early to say whether these medications are having a nationwide impact, Popkin said. Gallup's data is not a comprehensive look at the number of people using GLP-1s, nor does it cover whether the treatment was successful, how long they used the medication, or if the users dropped enough weight to move between weight categories. Because of off-label prescriptions and the drugs' use in controlling diabetes, it's also difficult to know if people reporting taking GLP-1s are obese, overweight, or a healthy weight, per their BMI category.

Until recently, more affordable, compounded versions of some of the most popular GLP-1 medications were widely available from local pharmacies because some brand-name medications were in shortage. Those shortage rules have now been lifted, making it harder to get inexpensive versions.

Because of lack of insurance coverage and cost, only a small percentage of people eligible to use the medications are on them, Ryder said. Looking at the situation beyond the Gallup numbers suggests the number being successfully treated is not likely enough to move the needle on national obesity numbers, he said.

The latest NHANES data raises another question: why is the severe obesity rate still rising if GLP-1s are reducing obesity, overall? The data suggests that 9.4% of the population has a BMI of 40 or higher, a number that rose from 7.7% in 2013-2014. In addition, the diagnosis of diabetes is at an all-time high according to Gallup's numbers, at 13.8% of the population.

People with BMIs over 40 and those with diabetes should be the ones most likely to be prescribed a GLP-1, according to medical criteria. There's a question as to why those numbers aren't going down as the number of people prescribed GLP-1s goes up, Popkin said, again raising questions about the data's limitations.

Medicare and Medicaid only cover the medications for patients with diagnosed diabetes or with obesity along with cardiovascular disease. On Nov. 4, the Trump Administration announced a deal to enable Medicaid and Medicare coverage of some GLP-1s for weight loss, alone for people with obesity and no related conditions. But whether this move will expand access will depend on the ultimate out-of-pocket cost for consumers, Ryder said.

"While I'm very hopeful that we'll start to see obesity prevalence decrease," he said, "that's going to coincide with better access to medications."

Changing the environment

Also adding to experts' skepticism about a turn in the obesity rate is the fact that little has changed about the food system in America. Policies put the onus on consumers to avoid prepackaged snacks high in sodium, saturated fat and added sugars, Parekh said.

"It's much cheaper to be unhealthier and buy unhealthy foods," she said.

For many, it's also a challenge to buy healthier foods. The U.S. Department of Agriculture estimates that 18.8 million Americans live in "food deserts" where it is difficult to access a full-service supermarket.

According to CDC data, 55% of the calories Americans consumed between 2021 and2023 were ultraprocessed, a somewhat nebulous category encompassing foods that are formulated from substances derived from foods — such as pure starch or fat — but that contain very little in the way of whole ingredients. These foods also tend to include additives not found in home kitchens, such as stabilizers and preservatives. They initially became a larger part of the American diet in the late 1970s, when the obesity rate started its rise.

Clinical and observational studies link high consumption of ultraprocessed foods to the development of obesity. This may be in part because they are hyperpalatable — in other words, very tasty — and thus encourage overconsumption, said Filippa Juul, an epidemiologist at SUNY Downstate Health Sciences University in New York. It may also be because the body may more easily break down these foods and use all their fats and sugars, compared to whole and less-processed foods that take more energy to digest.

"Even though you may think you're eating the same calories in almonds and potato chips, according to the label, you're actually eating less calories when you're eating the almonds, because you're not digesting it all," Juul told Live Science.

The Make America Health Again (MAHA) movement spearheaded by health secretary Robert F. Kennedy Jr. has drawn attention to ultraprocessed foods. But experts say there is little chance that MAHA will make major changes to how such foods are regulated.

There was initially interest from Trump's Food and Drug Administration (FDA) in looking at new labeling requirements for ultraprocessed foods, said Popkin, who was part of those conversations. However, when the administration released its MAHA Strategy in September, there was only one reference to labeling, which committed only to exploring the issue.

Popkin and his colleagues have found that clear warning labels can change real-world consumer purchases by alerting consumers to high levels of saturated fat, sodium, or sugar on the front of a product. Labels that use a red-yellow-green color-coded system to convey information about healthfulness are also effective, they have found.

But "instead of using our approach, which was valid and used in other countries, they are going back and saying we need more research," Popkin said. That position suggests it's unlikely that the U.S. will put new labeling regulations into play anytime soon, he said.

Meanwhile, the fate of the long-running NHANES survey that allows federal researchers to track the obesity rate is in the balance given ongoing cuts at the CDC. On Oct. 10, the team that runs the survey was fired. The next day, the decision was reversed for half of that team. A federal judge later blocked the remaining layoffs because they occurred during a government shutdown.

When it comes to ultraprocessed foods, "the MAHA movement is toothless," Popkin said. "Lots of talk, no policies or laws."