(Bloomberg) -- New research added to concerns about the downsides of shedding pounds with popular weight-loss shots.

A study done on Saxenda, an older daily weight-loss shot made by Novo Nordisk A/S that’s similar to newer treatments like Ozempic but considered less effective, reported that patients on the drug experienced a decline in bone density in the hips, spine and forearm.

The research, published Tuesday in the JAMA Network Open medical journal, didn’t include wildly popular shots such as Wegovy and Zepbound. But it’s likely that the loss of bone density would be similar — if not greater — from the newer shots because they lead to more weight loss, according to study author Signe Sørenson Torekov of Copenhagen University.

The boom in weight-loss shots has coincided with more worry about how shedding pounds can cause other problems. Drugmakers including Novo and rival Eli Lilly & Co. are racing to solve the loss of muscle some patients experience. 

Caloric restriction and hormonal changes from weight loss can lead to reductions in bone density, causing the bones to become more fragile. This can increase the risk of serious fractures in the hip, spine and wrist, especially among post-menopausal women and elderly adults.

Increased Mortality 

These kinds of fractures can lead to “increased morbidity and mortality, functional impairment and disability,” said John Batsis, an associate professor at the University of North Carolina’s school of medicine.

Declines in bone density are seen with any kind of major weight loss — whether through surgery, drugs or other means. But one hurdle to combat this health risk with people taking weight-loss drugs is that tests to measure bone health are not typically covered by insurance for such patients, according to Batsis. 

There also aren’t definitive guidelines for how to monitor bone health in these patients, according to Fatima Cody Stanford, an obesity medicine physician scientist at Massachusetts General Hospital. Meanwhile, people who get bariatric surgery to lose weight are routinely tested for bone and muscle loss.

The findings released Tuesday are a new analysis of a study first published in 2021 that tracked 195 participants with obesity who were treated with Saxenda, exercise or both. Researchers then did more work on the data to look at how the drug affected bone density.  

In the group that exercised alongside taking Saxenda, bone density was preserved, offering a potential solution for some patients. However, some experts worry that older adults will not be willing or able to follow the type of rigorous exercise program needed to maintain their bone strength. 

Kristen Beavers, an associate professor of nutrition and epidemiology at Wake Forest University, wants to conduct a study looking at osteoporosis medications to see if they help preserve bone density in weight loss patients. Dietary countermeasures, such as ensuring adequate calcium, protein and vitamin D consumption, are also key to musculoskeletal health, Beavers said.

The reason that bone loss during weight loss has received relatively little attention so far could be due to the long timescale, according to Beavers. While muscle loss can be measured within weeks, it takes four to six months for bone to turnover, drastically extending the time frame of bone loss studies.

The study received funding from the Novo Nordisk Foundation, the philanthropic organization that controls Novo Nordisk.

--With assistance from Naomi Kresge.

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