After a decade of increases, obesity rates among U.S. adults decreased last year.

Obesity rates among U.S. adults declined slightly last year, according to a study, but it was the first time in more than a decade that the country had seen a downward trend. Part of that may be due to the recent rise of blockbuster weight loss drugs like Ozempic, the study authors said.

The findings of the study were announced on Friday. Journal JAMA Health Forumthe most significant declines were seen in the South, especially among women and adults ages 66 to 75.

The study looked at BMI measurements for more than 16.7 million adults from 2013 to 2023 across different regions, age groups, genders, races, and ethnicities. BMI measurements are a standard but limited method for estimating obesity relative to body weight. Height to length was collected from electronic health records.

Researchers found that the adult obesity rate in the United States decreased from 46% in 2022 to 45.6% in 2023. (These are slightly higher rates than the U.S. adult obesity rate) Estimate from the centers for disease control and preventionThis means that from 2021 to 2023, approximately 40% of U.S. adults were obese. )

Benjamin Rader, a computational epidemiologist at Boston Children's Hospital and an author of the study, said the results were not uniform across demographics or geographic regions.

“Obesity has been on the decline in the United States as a whole, especially in the South, but this has not been the case in some regions,” he said. “Obesity among Black Americans also decreased significantly, but obesity among Asian Americans increased.”

Rader said the decline in the South was notable because the region observed the highest per capita intake of weight loss drugs, based on researchers' analysis of insurance claims. But he acknowledged that the possible link needed further investigation.

The study authors also noted that obese people in the South had a disproportionately high number of COVID-19 deaths, which may have influenced the overall data.

Dr. Michael Weintraub, an endocrinologist and clinical assistant professor at New York University's Grossman School of Medicine, said the results are consistent with the following: Recent data from the CDC Results showed a slight decrease in obesity prevalence among U.S. adults from 2021 to 2023 compared to 2017 to 2020 (although severe obesity increased during this period). ).

“This data is interesting and holds the promise that we may be on the cusp of changing this obesity epidemic,” said Weintraub, who was not involved in the new study. “However, I would hesitate to call the value of this downward trend in 2023 a trend.”

Even if weight loss drugs were the main factor in reducing obesity, experts say further studies over longer periods of time are needed to assess the true effects of new drugs.

“We know these drugs are very effective, but we need a few more years to see if this is really a trend, or if it's just a small spike and we're back to normal, or if things get much worse. Dr. Tannaz Moin, an endocrinologist and associate professor of medicine at the University of California, Los Angeles, said he was not involved in the study.

Moyn also pointed out that the new study only analyzed preparations of GLP-1 weight loss drugs (a category that includes Ozempic and Mounjaro). This type of drug is used to treat diabetes and obesity by reducing a person's appetite and food intake. This drug mimics the hormone that makes you feel full.

But GLP-1 drugs are only part of the prescription for treating obesity, and a more comprehensive study of different drugs could better capture changing trends, Moyn said. said. Weight loss drugs are also expensive, which can skew data about who can receive treatment.

Additionally, the study used insurance claims data, meaning those who were uninsured or who purchased weight loss drugs out of pocket were likely not included in the results.

Moin said he was surprised by the decline in BMI seen in older people.

“This group is not necessarily the group that I think is the biggest user of GLP-1 drugs, because a lot of them are in the Medicare age group,” she says, adding that weight loss drugs are the most popular for people on Medicare. may be difficult to obtain, he added. The Biden administration recently proposed a rule that would require Medicare and Medicaid to cover weight loss drugs for people seeking obesity treatment.

However, Weintraub cautioned that the observed decline does not necessarily indicate a long-term decline.

“We've been fooled until now by fluctuations in obesity prevalence,” he says. “We were excited about the downward trend in childhood obesity rates announced by the CDC in the early 2000s, but in the years since, obesity rates have increased even more.”