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Here's How Ozempic Actually Works for Weight Loss

There’s an abundance of drugs whose mechanisms are surprisingly complex. Popular diabetes and weight-loss treatments like Ozempic and Wegovy are two such drugs.

By Sean MowbrayMay 7, 2024 8:00 AM
Ozempic injection pens and box. Ozempic is a medication for diabetes
Ozempic is FDA-approved for treating diabetes, while Wegovy is FDA-approved for treating obesity. Both drugs contain the same active ingredient, semaglutide, which may have weight-loss effects. (Credit: Marc Bruxelle/Shutterstock)


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Though initially intended to treat diabetes, Ozempic has acquired another application in recent years. Heralded as a wildly effective weight-loss drug, it provides millions of people with obesity an alternative route for reducing their weight, albeit a financially costly one.

Yet this weight-loss effect is sometimes described as simple “serendipity,” and a full understanding of how this drug works has yet to be achieved.

Read More: What Factors Matter Most For Weight Loss?

Ozempic Takes Away Cravings

Ozempic is an injectable treatment administered once a week. The U.S. Food and Drug Administration (F.D.A.) approved a smaller dose of the drug for treating diabetes in 2017, as well as a larger dose of the drug for treating obesity in 2021, branded under the name Wegovy. As GLP-1 agonists, their active ingredient is semaglutide, which mimics a naturally occurring hormone called glucagon-like peptide-1 (GLP-1).

“We make these hormones when we eat,” says Samir Malkani, a endocrinologist at the UMass Chan Medical School’s Department of Medicine.

Secreted in the gut, GLP-1 stimulates the pancreas to produce insulin, reducing the body’s blood sugar. That’s why GLP-1 agonists are effective for treating diabetes. But there are also receptors for the GLP-1 hormone in the brain, heart, and other parts of the body, meaning that GLP-1 and its artificial counterpart also trick the mind, triggering a feeling of satiety.

“There are feeding centers in the brain that make us hungry and crave food,” Malkani says. “So this center in the brain is what the GLP-1 receptor drugs like Ozempic bind to [to] take away that craving.”

Read More: The Difference Between Zepbound and Ozempic, and How They Work

Ozempic Can Decrease Cravings

Ozempic aids weight loss, experts say, particularly when combined with diet and exercise. Though figures differ amongst individuals, a 68-week study from 2021 found that around half of those who use semaglutide lose 15 percent of their body weight, while around a third lose 20 percent of their body weight.

Unlike the naturally occurring hormone, semaglutide lasts far longer in the body, increasing a user’s feeling of fullness and reducing their appetite.

“The hormone is secreted in response to eating, and it circulates in our blood for a few minutes,” Malkani says.

But semaglutide circulates in our blood for days, and has a better chance of reaching the brain’s GLP-1 receptors.

“Accessing that receptor in the brain actually gives other features to that drug that the natural hormone doesn’t have, in that it reprograms the way appetite and fullness are felt, so that people tend to eat less,” adds Sebastian Furness, a biochemist with the School of Biomedical Sciences at the University of Queensland.

It’s also suggested that these drugs can lead to lower cravings for alcohol and nicotine, another unexpected outcome. “I have literally thousands of people on the medication and only a handful of people will come and say, ‘It’s taking away my craving for alcohol,’” Malkani says.

Studies on the drug’s potentially anti-addictive effects are ongoing. But research also suggests that these drugs could be beneficial for reducing a host of other risks, too, such as cardiovascular disease and liver disease, and possibly more.

Read More: These 10 Weight Loss Drugs Like Ozempic Can Work, But Are They Safe?

There are Still Risks

Experts say that Ozempic’s efficacy in tackling diabetes and obesity is not in doubt, but that doesn’t mean that it isn’t without its own risks and side effects. Gastrointestinal issues, including nausea, vomiting, and constipation, are amongst those incurred by Ozempic. In triggering the feeling of fullness, these drugs also slow down the stomach and instances of severe gastroparesis, or stomach paralysis, are possible. There are also concerns of possible connections to pancreatitis and mental health issues.

These side effects lead experts to underline that taking Ozempic should always be in consultation with a health professional.

“If you have heart disease, diabetes, and are overweight, I would recommend it. If you have heart disease and are overweight, I would recommend it,” Malkani says. “For people who are overweight, but are otherwise healthy, we need to have a discussion.”

In his view, medical professional should first suggest other approaches for weight loss — such as lifestyle changes — that can be adopted prior to the drug route. In fact, one of the concerns about semaglutide is that those who stop using the drug will most likely regain the weight they lost as its effects wear off in the absence of significant lifestyle changes.

“I think it’s important for people to know that before they get into the drug,” Malkani says. “Currently, we don’t have a good way for a person who’s lost the weight on the drug to keep the weight down without being on the drug for a long time.”

New Ozempic-style drugs are on the horizon, combining different hormones that some believe show even greater promise. But as these remedies advance, questions remain about the exact role and long-term effects they have on the bodies of those who use them. It’s clear there are gaps in our knowledge of how Ozempic and other GLP-1 agonists work, but then again, Furness says, that’s also true for many other long-standing medicines as well.

“There’s a philosophical question, right? Do you need to know how medicine works for medicine to be useful? I don’t know whether that’s true,” he says. “We know enough about it to use it as a medicine for both type two diabetes and for obesity.”

Read More: Forget Dieting. Here’s What Really Works to Lose Weight

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

Sean Mowbray is a freelance writer based in Scotland. He covers the environment, archaeology, and general science topics. His work has also appeared in outlets such as Mongabay, New Scientist, Hakai Magazine, Ancient History Magazine, and others.

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