Less than a fifth of large companies in the United States include coverage for the popular but pricey weight loss drugs Wegovy and Zepbound in their health insurance plans, according to a survey published Wednesday in Health Affairs.

Among the large firms that do cover them, a third say the coverage has a “significant impact” on their plans’ prescription drug spending.

“Employers are really trying to thread the needle right now,” said study author Matthew Rae, associate director for the program on the health care marketplace at KFF, a nonprofit group that researches health policy issues. “They’re trying to figure out what is the right balance between the advantages to employees, potential health benefits and the cost of these drugs. And at this point, all of those things aren’t sorted out.”

About 154 million people get health insurance through their jobs, according to KFF. The survey, taken from January through July, included responses from more than 2,100 employers that have at least 200 workers and that offer health benefits.

Half of the employers said they don’t cover the drugs, while almost a third — 31% — said they don’t know if they cover them; fewer than 1 in 5 said they do provide coverage.

Rae said that when the researchers looked specifically at America’s largest firms — with 5,000 or more workers — those didn’t fare much better: More than a quarter said they do cover the drugs and almost two-thirds say they don’t.Dr. Susan Spratt, an endocrinologist and senior medical director for the Population Health Management Office at Duke Health in North Carolina, called the results “disheartening,” adding that many people who need the medications aren’t getting it.

“People who are rich can afford to pay the $1,000 per month for this medication,” she said. “We are just widening health disparities by making it harder for patients to access life-changing medication.”

About 40% of adults in the U.S. have obesity, according to the Centers for Disease Control and Prevention. While obesity rates have remained stable over the past decade, rates of severe obesity have increased, from 7.7% to 9.7%. 

Dr. Christopher McGowan, a gastroenterologist who runs a weight loss clinic in North Carolina, said that there is a tendency to blame employers and insurance companies for the lack of coverage, but that blame is being “misdirected.” 

Wegovy, from Novo Nordisk, and Zepbound, from Eli Lilly, can cost more than $1,000 for a month’s supply. Research has shown that coverage for the drugs can have significant cost implications for employers, as well as state and federal governments. Earlier this year, North Carolina announced that it would stop providing coverage of the weight loss drugs for its employees after it was projected that it would cost the state more than $600 million within the next five years.

“The root of the problem is cost. Plain and simple,” McGowan said. “It’s economically impossible to provide coverage for everyone in need without drastically hiking rates or putting health plans at risk of bankruptcy.”

Rae said that right now, the cost is untenable for employers. 

“The average health insurance premium is $25,000 for a family of four, just over $8,000 for a single person,” he said, a cost covered by both employers and employees. “If you’ve got a third of your workers taking a $10,000 drug, that’s obviously going to have a significant impact.”

Novo Nordisk and Eli Lilly did not respond to requests for comment.

The survey found that about half of employers that cover the weight loss drugs have certain requirements associated with their coverage, which Rae said would limit access for some employees but save money. 

The requirements can include meeting with a dietitian or participating in a lifestyle or weight-loss program either before or while taking the drugs.

Among large firms that don’t currently cover GLP-1 drugs for weight loss, only about 3% said they’re “very likely” to do so in the next year. About a quarter said they’re somewhat likely to do so.

Despite the exorbitant cost, employers do have a positive view of the drugs.

The survey found that among all large firms, nearly half said it will be “very important” or “important” to cover GLP-1 drugs for their employees’ satisfaction with their health plan.