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Research & Innovation

How Anti-Obesity Medications Can Help With Surgery


Doctors discuss the benefits of using anti-obesity medications before orthopaedic and bariatric procedures.

[Originally published: April 2, 2024. Update: June 24, 2024.]

Wegovy®, Zepbound®, and similar medications continue to gain attention for effectively treating obesity, and now there is discussion—with research underway—about their potential for improving certain surgical outcomes.

The brand-name medications mentioned above belong to a class called GLP-1 (glucagon-like peptide-1) agonists. GLP-1s mimic the actions of the GLP-1 hormone, which is secreted in the gut and sends an “I’m full” signal to the brain after you eat.

GLP-1 medications aren’t new. Ozempic® (generic name: semaglutide) received approval from the U.S. Food and Drug Administration (FDA) to treat type 2 diabetes in 2017. After its weight-loss effects were studied, semaglutide (at a higher dose and sold under the name Wegovy) was approved by the FDA as an anti-obesity medication in 2021, and others have since followed.

Most recently, the FDA approved Wegovy for patients with cardiovascular disease and obesity or overweight after a study showed that those taking the medication had a lower overall risk of major cardiac events, such as heart attack, stroke, or cardiovascular-related death. And a recent study published in The New England Journal of Medicine found that tirzepatide (part of the class of GLP-1 drugs) might be useful for those with obstructive sleep apnea.

Now, some Yale Medicine surgeons believe, based on their ongoing research, that taking anti-obesity medications before and sometimes after total joint replacement and bariatric surgery can be beneficial.

“These medications have been transformative, in terms of expanding the pool of people who can safely undergo joint replacement surgery,” says Daniel Wiznia, MD, a Yale Medicine orthopaedic surgeon and co-director of the Avascular Necrosis Program. “These anti-obesity medications are game-changers; they are changing the way people practice medicine.”

Often, patients who need a total hip or knee replacement must delay surgery until they lose enough weight to meet specific body mass index (BMI) standards. This is important in protecting the patient’s health. “Weight increases a patient’s risk of postoperative complications, including wound-healing problems, stroke, heart attack, blood clots, and infection,” he says.

However, having patients take a GLP-1 medication before surgery, as well as improving their diet, has allowed more patients to reach a safe preoperative BMI, Dr. Wiznia says.

Likewise, John Morton, MD, MPH, medical director of bariatric surgery for the Yale New Haven Health System, says he has found that putting patients on GLP-1s before weight-loss surgery helps them achieve better results.

Still, there are many unknowns, including whether patients will need to stay on anti-obesity medications after surgery and whether insurance will cover the cost of the drugs.

Below, we talk more with Drs. Wiznia and Morton about the use of anti-obesity medications before surgery.

How are anti-obesity medications used to help people who need joint replacement surgery?

Someone might need a total hip or knee replacement if they have arthritis, broken bones, or other orthopaedic conditions, and more conservative treatment options (such as medications or modifying daily activities) have not helped.

In the United States, more than 790,000 total knee replacements and more than 450,000 total hip replacements are performed each year, and those numbers are expected to grow as the Baby Boomer population ages. Obesity, which affects about 42% of adults, is also believed to be a major factor in driving up the number of total joint replacements. That’s because excess weight puts additional stress on weight-bearing joints.

Because people with obesity have a higher risk of complications during and after surgery, some surgeons, hospitals, and insurance carriers have BMI cut-offs for patients undergoing elective joint replacement surgery. For example, institutions may require that patients have a BMI within a certain range, such as between 35 and 40, in order for their joint replacement surgery to be covered by insurance. (BMI is determined by dividing your weight by the square of your height. Obesity is defined as 30 and above.)

“If I am operating on someone with obesity, the surgery is far more complex—for instance, we will need special implant devices, closure devices, and surgical tools,” Dr. Wiznia says.

If a patient with obesity needs joint replacement surgery, Dr. Wiznia says he works with them to explore weight-loss options, including a referral to the Yale Medicine Center for Weight Management to consider anti-obesity medications or bariatric surgery.

“I tell my patients that if they can get to a certain weight, we can do the joint replacement surgery with a potentially lower risk of complications. Some patients want to start by working on their diet; some want to try medications. I can also refer them to a nutritionist, or they can work with their primary care physician or an endocrinologist,” Dr. Wiznia says.

Can anti-obesity medications and bariatric surgery work together?

When it comes to weight loss, it doesn’t have to be a choice between anti-obesity medications and bariatric surgery—the two can work together, says Dr. Morton, who is also board-certified in obesity medicine.

“We know that losing weight before an elective surgery can decrease the risk of complications. Because of this, we have been advocating for weight loss prior to orthopaedic and hernia procedures,” Dr. Morton says. “I treat hernias, which often occur in patients who are heavier and sicker. We want to prepare them for surgery and get their weight down a little before surgery. We have data showing that people who lose weight before surgery do better after surgery.”

Bariatric surgery patients with a BMI higher than 50 are at higher risk for complications, Dr. Morton says. “So, we find that having patients use the GLP-1 medications before surgery helps.”

Do patients need to stay on anti-obesity medications after surgery?

Because obesity is recognized as a chronic metabolic disease, patients who start taking anti-obesity medications for weight loss should expect to stay on them for a long time, possibly for life, the doctors say.

However, this might not be the case for a patient undergoing bariatric surgery, which alters the GLP-1 hormones.

“We are researching this now—if it’s necessary to continue the drug after surgery, once you’ve achieved significant weight loss prior to surgery,” Dr. Morton says. “The other question is if the response to the drug predicts the response to surgery. For example, would everyone benefit from taking these medications before surgery? Or are there some cases where they are not needed, and surgery alone will help them?”

Immediately after bariatric surgery, patients are taken off their GLP-1s because the body needs to adjust physiologically, Dr. Morton says. “We don't want to add an element of uncertainty in terms of potential side effects from anti-obesity medications, which can make the patient more nauseated,” he explains. “About three months after surgery, we can decide if a patient needs to go back on the medication.”

That decision, he says, is based on a risk-benefit calculation. It determines the appropriate amount of weight loss for each patient based on their demographics and BMI. “If patients don’t reach their number after surgery, we would then put them back on an anti-obesity medication. But based on my experience, that has only occurred in about 5% to 10% of cases,” he says.

One potential hurdle is insurance coverage. “But the more we learn about the additional health benefits from these anti-obesity medications, the greater the potential for broader coverage for more people,” says Dr. Morton.