Just over 40% of Americans are obese based on BMI, and that number has been increasing since the mid-1970s. However, some new statistics suggest that obesity rates are now plateauing or declining.
Does this mean America has reached its heaviest weight? Experts aren’t so sure.
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For researchers, none of this news signals a change in obesity trends.
“This is not the time to relax,” Niyati Parekh, a professor of public health nutrition at New York University, told Live Science.
latest numbers
Obesity is defined as a body mass index (BMI) of 30 or higher, and “severe” obesity (also known as class III obesity) is defined as 40 or higher. This measurement of body fat based on height and weight is an imperfect way to diagnose an individual’s health. For example, a person with a very muscular build may be considered overweight or obese despite having a healthy body composition. However, it is used by public health officials to understand how much of the population is overweight and obese.
Obesity is associated with chronic health problems such as sleep apnea, cardiovascular disease, liver disease, and diabetes.
Obesity rates began to rise across all groups in the United States 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% did. The latest data collected between 2021 and 2023 shows that 40.3% of adults are obese.
The recent age-adjusted increase was not a statistically significant change compared to the previous decade, suggesting that obesity rates are no longer rising. But Barry Popkin, a professor of nutrition at the University of North Carolina who focuses on evaluating food labeling and obesity policies, said the National Health and Nutrition Examination Survey (NHANES), which derives these numbers, has limitations.
Although the survey is a national sample, Popkin said regional and seasonal comparisons are not possible because northern areas are surveyed in the summer and southern areas in the winter. More importantly, the study compares the 2021-2023 numbers to 10 years ago, which is just two data points.
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“We’ve seen short-term stagnation at various points in the past,” Popkin said. For example, there was a brief lull in the rise from 2009 to 2012, but thereafter it was only a temporary dip in a continuing upward trajectory.
According to the latest Gallup National Health and Welfare Index released on October 28, the overall obesity rate among U.S. adults will be 37% in 2025, down from the survey’s highest rate of 39.9% in 2022. But even that data is questionable, said Justin Ryder, associate professor of surgery and pediatrics at Northwestern Feinberg School of Medicine and associate director of research in the Lurie College of Surgery. Children’s Hospital of Chicago.
Gallup surveys about 5,000 adults every quarter, but it’s unclear how many people in that sample have a BMI in the obese range, given that participants are not nationally representative by weight status.
Ryder said small sample sizes can skew the picture. More than a decade ago, he said, data suggested that obesity rates among children ages 2 to 5 were declining. But it turned out that the trend was based on just 700 children, and the results evaporated by the next year’s data collection. Ryder told Live Science that he is skeptical of Gallup’s data for similar reasons.
“I can’t believe it,” he said.
Role of GLP-1
In a report on its findings, Gallup suggested that new drugs that target the glucagon-like peptide 1 (GLP-1) receptor may be influencing obesity rates in the United States. These drugs, known by brand names such as Ozempic and Zepbound, regulate blood sugar levels and slow stomach emptying, 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. Gallup’s numbers show that obesity rates have declined the most among people ages 40 to 64, which coincides with the highest intake of GLP-1 drugs.
But overall, Popkin said it’s too early to tell whether these drugs are having a national impact. Gallup’s data is not a comprehensive look at the number of people using GLP-1, nor does it cover whether the treatment was successful, how long the drug was used, or whether users lost enough weight to move between weight categories. Because of off-label prescribing and the drug’s use in controlling diabetes, it is also difficult to know whether people who report taking GLP-1 are obese, overweight, or at a healthy weight by BMI category.
“We’re very hopeful that obesity prevalence will start to decline, but at the same time access to medicines will improve.”
Justin Ryder, Northwestern
Until recently, more affordable compound versions of some of the most popular GLP-1 drugs were widely available at local pharmacies due to shortages of some branded drugs. Nowadays, these scarcity rules have been abolished, making it difficult to obtain cheaper versions.
Ryder said only a small number of people have access to the drug due to lack of insurance coverage and cost. Looking beyond Gallup’s numbers, he said the numbers for successful treatments likely won’t be enough to significantly change national obesity numbers.
The latest data from NHANES raises another question. If GLP-1 is reducing obesity overall, why are rates of severe obesity still rising? This data suggests that 9.4% of the population has a BMI of 40 or higher, an increase from 7.7% in 2013-2014. Furthermore, according to Gallup statistics, 13.8% of the population has been diagnosed with diabetes, an all-time high.
According to medical standards, people with a BMI over 40 and people with diabetes should be most likely to be prescribed GLP-1. Popkin said there were questions about why the numbers weren’t going down as the number of people prescribing GLP-1 increased, again raising questions about the limitations of the data.
Medicare and Medicaid only cover medications for patients diagnosed with diabetes or obese patients with cardiovascular disease. On November 4, the Trump administration announced an agreement that would allow Medicaid and Medicare coverage of some GLP-1 for weight loss, but only for people who are obese and do not have associated medical conditions. But whether the move expands access will depend on consumers’ final out-of-pocket costs, Ryder said.
He said: “I’m very hopeful that obesity prevalence will start to decline, but at the same time access to medicines will improve.”
change the environment
The fact that there has been little change in the U.S. food system also adds to experts’ skepticism about changes in obesity rates. Parekh said the policy puts the onus on consumers to avoid prepackaged snacks that are high in sodium, saturated fat and sugar.
“It’s much cheaper to be unhealthy and buy unhealthy food,” she says.
For many people, purchasing healthier food is also difficult. The U.S. Department of Agriculture estimates that 18.8 million Americans live in “food deserts” where full-service supermarkets are difficult to access.
According to CDC data, 55% of the calories consumed by Americans between 2021 and 2023 were ultra-processed, a somewhat nebulous category that includes foods made from food-based substances such as pure starches and fats, but with little in the way of whole ingredients. These foods tend to contain additives not found in home kitchens, such as stabilizers and preservatives. They first became a large part of the American diet in the late 1970s, when obesity rates began to rise.
Clinical and observational studies have linked high consumption of ultra-processed foods to the development of obesity. Philippa Joule, an epidemiologist at the State University of New York Downstate Health Sciences University, said part of the reason may be that they are highly palatable, or in other words, very tasty, which may encourage overconsumption. It may also be because your body breaks down these foods more easily and uses up all the fat and sugar content compared to whole foods and less processed foods, which require more energy to digest.
“Even though you think almonds and potato chips have the same amount of calories, according to the label, when you’re eating almonds, you’re actually taking in fewer calories because you’re not digesting them all,” Juhl told Live Science.
The Make America Health Again (MAHA) movement, led by Secretary of Health Robert F. Kennedy Jr., is drawing attention to ultra-processed foods. But experts say MAHA is unlikely to make any major changes to how such foods are regulated.
Popkin, who attended the meeting, said there was initial interest from President Trump’s Food and Drug Administration in considering new labeling requirements for ultra-processed foods. However, when the government announced its MAHA strategy in September, there was only one mention of labeling and only a promise to investigate the issue.
Popkin and colleagues found that clear warning labels on the front of a product that alert consumers to high levels of saturated fat, sodium, and sugar can change consumer purchases in the real world. Researchers found that labels that convey health information using a red, yellow, and green color-coding system were also effective.
But “instead of using our approach, which has worked and been used in other countries, they go back and say more research is needed,” Popkin said. This position suggests that the U.S. is unlikely to introduce new labeling regulations anytime soon, he said.
Meanwhile, the fate of the long-running NHANES study, which allows federal researchers to track obesity rates, is in limbo given continued cuts by the CDC. On October 10th, the team running the survey was fired. The next day, half of that team reversed its decision. A federal judge later blocked the remaining layoffs, saying they occurred during the government shutdown.
When it comes to ultra-processed foods, “the MAHA movement is in vain,” Popkin said. “There’s a lot of talk, but no policy or law.”
This article is for informational purposes only and does not provide medical advice.
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