A new class of weight loss drugs has been grabbing headlines and attention from consumers who live with obesity or Type 2 diabetes — and for good reason: They can produce impressive weight loss results.
But these medications are not for everyone, and they do carry a risk of considerable side effects. Plus, there is some data that shows they have to be taken long term to maintain weight loss.
That’s why it’s important for consumers to know about the potential risks versus benefits that are associated with these medications.
Weight Loss Drugs: How They Work
Two of the new drugs — Ozempic and Wegovy — are glucagon-like peptide-1 (GLP-1) receptor agonists.
“Ozempic and Wegovy are the same drug (semaglutide), but they’re marketed differently: Ozempic for Type 2 diabetes, and Wegovy for weight loss,” explains Dr. Lawrence Cheskin, professor of nutrition and food studies at George Mason University and an adjunct professor of medicine at Johns Hopkins School of Medicine.
Two other new medications — Mounjaro and Zepbound — are a combination of GLP-1 agonists and a glucose-dependent insulinotropic polypeptide (GIP) known generically as tirzepatide. Mounjaro is approved by the Food and Drug Administration for Type 2 diabetes, while Zepbound is approved for weight loss.
All of these drugs are self-administered by injection once a week.
The GLP-1 drugs work by stimulating insulin secretion after meals, increasing satiety and slowing stomach emptying, all of which help people feel full for longer.
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Are Weight Loss Drugs Effective?
GLP-1 weight loss medications are highly effective, typically resulting in a weight loss of 5% to 20%.
“They reduce the number of calories people consume by hundreds,” says Dr. Robert Kushner, an obesity medicine specialist and professor of medicine at the Northwestern University Feinberg School of Medicine in Chicago. “People taking these drugs stop eating much sooner than other people around the table, and they reduce snacking. People are less enticed by food between meals.”
A study in a 2021 issue of The New England Journal of Medicine found that when adults with a body mass index of 30 or greater took a once-weekly injection of 2.4 milligrams of semaglutide, while also making lifestyle changes, they lost an average of 15% of their body weight after 68 weeks. By contrast, a study in a 2022 issue of The New England Journal of Medicine found that when adults with a BMI of 30 or more took 15 milligrams of tirzepatide, they lost an average of 22.5% of their body weight in 72 weeks.
“These drugs really are game-changers,” Cheskin says.
The weight loss that occurs with these drugs can have other positive effects.
“On average, people are getting significant health benefits from these, including a reduction in heart attacks, strokes and all-cause mortality,” notes Dr. Fatima Cody Stanford, an obesity medicine physician at Massachusetts General Hospital and Harvard Medical School.
[READ Does Medicare Cover Ozempic?]
Side Effects of Ozempic, Wegovy, Mounjaro and Zepbound
Ozempic, Wegovy, Mounjaro and Zepbound all carry a risk of side effects.
The most common side effects for all four drugs include:
— Nausea.
— Vomiting.
— Diarrhea.
— Constipation.
— Heartburn and acid reflux (including burping).
— Bloating.
“We’ve seen people have tolerance issues to all of these,” Kushner says. “It varies from person to person.”
These side effects typically occur when someone first starts taking the drug, and they dissipate as their body gets used to it.
“We’ve learned that by starting with a low dose and escalating it slowly over four months, we can lower the side effect profile significantly,” Kushner says, adding that the side effects usually diminish to a low level or become episodic over time.
While most people do adapt to these medications over time, some — 10% to 20% — don’t, Cheskin says.
Important warnings
As with significant weight loss in general, some people who take these drugs may experience muscle loss and lower bone density — which could increase the risk of injury, particularly for older adults.
It’s important to note that animal studies have shown that semaglutide injections may increase the risk of thyroid cancer, including medullary thyroid carcinoma. However, current evidence cannot definitively confirm whether the medication may carry the same risk in humans.
To be safe, tell your doctor if you or one of your family members has a history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome and if you experience any of the following thyroid symptoms:
— A lump or swelling in the neck.
— Hoarseness.
— Difficulty swallowing.
— Shortness of breath.
In 2023, the FDA issued a warning about the potential for intestinal blockage associated with semaglutide, after receiving reports from people taking the drug. Cheskin and Kushner say, however, that they haven’t seen intestinal blockages among people taking these medications.
“Because they slow gastric emptying and can cause vomiting, they can simulate intestinal blockage, but they don’t cause an intestinal obstruction,” Cheskin says.
How to reduce the risk of side effects
To mitigate the side effects, here are a few strategies that can help:
— Pay attention to the quality and timing of your diet. It’s important to reduce fat in the diet and stick with a regular eating schedule. “Have a small amount of food that’s nutritious and healthy a few times per day,” Kushner says. “You still need to nourish your body.”
— Eat slowly.
— Listen to your body’s signals. Learning to listen to your body’s cues will help you know when to stop eating before you feel full.
[READ: How to Calculate Weight Loss Percentage.]
Long-Term Side Effects of Weight Loss Drugs
Because these drugs haven’t been used for very long, little is known about long-term side effects. However, no lasting issues have emerged so far, experts say.
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Side Effects of the New Weight Loss Drugs: Are They Safe? originally appeared on usnews.com
Update 02/06/24: This story was previously published at an earlier date and has been updated with new information.
