Obesity rates have decreased slightly in the US and while it’s too early to say whether the trend will hold and what’s causing the change, experts believe weight-loss drugs could be playing a role in continuing to lower obesity and reduce related health risks.
These medications – Ozempic, Wegovy, Mounjaro and others – are called GLP-1 agonists, and they were originally developed to treat type 2 diabetes. But they also show great promise for treating obesity and other health conditions, like heart disease, kidney and liver issues, sleep apnea, asthma, Covid complications and cancer, among others.
“Everything that has to do with obesity gets better,” says Rozalina McCoy, an associate professor of medicine at University of Maryland and lead author of a Nature study showing the benefits of GLP-1s on cardiovascular health among people with type 2 diabetes.
The drugs “transformed” diabetes care, because they actually improved health outcomes – a first for type 2 diabetes, she said. They can help prevent heart attacks, strokes, kidney disease, and death. Other conditions, like metabolic dysfunction-associated steatotic liver disease (formerly known as fatty liver disease), also didn’t have effective treatments before.
“Usually I think nothing works, everything’s overplayed,” said Jeremy Faust, an emergency physician at Brigham and Women’s hospital and assistant professor at Harvard Medical School. But “I am really, really exuberant about the possibilities here.”
The obesity rate for US adults over the age of 20 was 41.9% in 2017–2020, but it dropped to 40.3% in 2021–2023, according to the National Center for Health Statistics. Severe obesity rose from 9.2% to 9.7% at the same time.
This isn’t the first time the overall rate has dropped. Obesity has climbed fairly steadily in the US over recent decades, but there were small drops in 2007–2008 and 2011–2012, for instance, that were followed by increases.
The rise in severe obesity is concerning, because that’s the group at highest risk of poor health, McCoy said. “I don’t look at that study as being reassuring. I think it’s a sign that we’re still heading in the wrong direction.”
But “at least it’s not going up”, said John Morton, an obesity doctor and vice-chair of bariatric surgery at Yale School of Medicine.
It usually takes years of data to determine trends, and peaks are usually only visible long after reaching them, he said. “I think we still have a lot of work to do, but it’s maybe a faint glimmer that it might be plateauing.”
It’s “certainly a possibility” the GLP-1s are responsible for the slight decrease in obesity, Morton said, but he cautioned that there were also other factors at play.
“Another possibility might be Covid. The two leading risk factors for Covid mortality were age and weight,” he said. “So I don’t know what to make of it yet.”
He also pointed out that rates of obesity among young people were unusually high, so “we have another epidemic coming”.
But he welcomes the interest – and the scrutiny – around obesity treatment. “It’s really been a struggle, getting attention to the issue,” he said.
He is “grateful” for the GLP-1 drugs because they offer patients more options, and because they have prompted conversations about the health effects of obesity.
He believes they can play a role in improving obesity and other health conditions, particularly if there’s a formulation of the drugs that can be taken orally instead of injected. “It’s really going to be a population benefit,” he said.
“What surprised me was how soon it worked – how early the mortality benefit showed up,” said Faust. He compared having high-risk conditions from obesity to being closer to the edge of a cliff. The drugs seem to help pull the patients back from the edge. “Suddenly, someone who was ‘supposed’ to die in a year doesn’t, and it’s remarkable to me,” he said.
Faust even hypothesized that the rise in severe obesity could be a reflection of high-risk patients living longer because of better treatments – when a higher number of people enter this category than those who leave it, the rate would go up, he theorized.
About one in eight (12%) of American adults say they have ever taken a GLP-1 agonist, with 6% saying they are on one of the medications now. About half of them say it is difficult to afford the drugs.
Since 2018, the company offering Ozempic and Wegovy, Novo Nordisk, has made $50bn in sales – 72% of which came from the US.
This high cost is one of the reasons why McCoy doesn’t believe GLP-1s will affect rates of obesity in much of the population.
“Medications that are $1,000 a month and are accessible to a select few – that’s not how we solve public health problems like obesity,” McCoy said. “They’re effective treatments that we need to have access to and use. But if we’re going to actually tackle the problems of obesity and diabetes and cardiovascular disease, we need to get at the underlying cause of what is causing this in the first place.”
Yet others are more optimistic about the role GLP-1s can play in reducing obesity across the population.
“We have turned obesity into some kind of moral sin, instead of what it is, which is a metabolic problem,” Faust said. Paying attention to diet and healthy practices is admirable, he said, but “we’ve been trying that for a long time. Let’s play the board we have, not the board we wish we had.”
Prevention is important, “but you kind of have to have both”, Morton said. “You’ve got to have both prevention and treatment in order to really combat this, just like we did with heart disease and cancer.”
People who go off the medication regain about two-thirds of their weight. But it’s not unusual for people with chronic conditions like asthma, high cholesterol or high blood pressure to take medications for long periods of time, even for the rest of their lives.
“We don’t go into treating other health conditions by saying, ‘Well, we don’t know if we should treat your high blood pressure because we may have to stop taking this medication in the future,’” McCoy said. “I think these questions come with obesity in part because of the stigma that obesity carries … It is a serious chronic health condition that we should treat.”
The side-effects include nausea and vomiting, and rare side-effects include stomach paralysis, small bowel blockage and pancreatitis. Given these potential risks, the medications should only be given to those who need them, the experts said.
“Honestly, it’s going to be patients with obesity as well as diabetes – those are the patients who have the highest risk of adverse health events and they’re going to benefit the most,” Morton said. For these patients, the benefits often outweigh the potential risks.
“The GLP-1 drugs have actually been around for over 20 years,” Morton said. “If we were going to see a lot of complications, we probably would have seen them already.”
Now that the benefits for related health conditions are becoming clearer through research, it’s possible that insurance will cover more of the treatments – because insurance plans like Medicare won’t cover obesity treatments, but they can pay for treatments that reduce the risk of cardiovascular disease, sleep apnea and other conditions.
Researchers are also looking into the potential for these drugs to treat substance use disorder, Alzheimer’s, Parkinson’s, mental health and other issues. But those connections have not been as well-established as other health benefits.
“We have to be cautious, because it very well could be that there are a slew of other diseases, ranging from addiction to mental health, that these drugs could be equally amazing for,” said Faust. “But I think that we don’t want to get ahead of ourselves.”
