These five peptide-containing medications have been shown to help people lose weight.

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Medications like Wegovy and Zepbound receive plenty of buzz for their ability to help people lose weight. The two have a few things in common, mainly, peptides for weight loss. Wegovy (semaglutide) belongs to a class of medications known as glucagon-like peptide-1 (GLP-1), and Zepbound (tirzepatide) is both a GLP-1 and glucose-dependent insulinotropic polypeptide (GIP).

But here’s the thing: Not all peptides are designed for weight loss, although research has found that it’s usually a common side effect. A good example is Ozempic, which has become popular for medicated weight loss, despite technically being a drug to help with blood sugar management in patients with type 2 diabetes.

Meet the experts: Keri Gans, R.D., author of The Small Change Diet; Christoph Buettner, M.D., Ph.D., is chief of the division of endocrinology at Rutgers Robert Wood Johnson Medical School; Mir Ali, M.D., is a bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA.

If you’re interested in using peptides for weight loss, there are options. Here’s what you need to know about the types of peptides, how each works, and potential side effects to keep in mind.

What are peptides?

You may have heard of peptide serums for healthy skin, and that’s because the ingredient is in so many things. “Peptides are a string of amino acids structurally similar to protein but smaller,” says Keri Gans, R.D., author of The Small Change Diet. Peptides usually contain less than 50 amino acid chains, says Christoph Buettner, M.D., Ph.D., chief of the division of endocrinology at Rutgers Robert Wood Johnson Medical School.

“Peptides play crucial roles in various biological processes within the body, acting as signaling molecules, hormones, and enzymes,” Dr. Buettner says. “There are thousands of peptides in our body doing many different things.”

Do peptides work for weight loss?

Yes, peptides can work for weight loss—but not all peptides will impact the number on the scale. “Asking if peptides can be used for weight loss is akin to asking whether drugs can be used for weight loss,” Dr. Buettner says. “There are a gazillion drugs that cannot be used for weight loss, but then there are some that can. The same applies to peptides.”

Peptides that work for weight loss will usually slow the movement of food through the gut and reduce cravings among other things, says Mir Ali, M.D., a bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA.

What types of peptides work for weight loss?

There are a bunch. “GLP-1 receptor agonist medications are formulated to stimulate peptide production in the body to slow stomach emptying,” Dr. Ali says. “Dual GIP/GLP-1 receptor agonists are involved in digestion, hunger, and satiety.”

“Both of these hormones/peptides are attractive candidates for weight management,” Dr. Buettner says.

Several peptides can work for weight loss, but these are the most common ones on the market right now:

• Semaglutide (Ozempic, Wegovy). Semaglutide is a GLP-1 receptor agonist and includes Ozempic (which, again, is designed to treat type 2 diabetes) and obesity (Wegovy). Both are injectable medications approved by the Food and Drug Administration (FDA). The Ozempic website points out that people on the drug have lost up to 14 pounds, but also stresses that it’s “not a weight loss drug.” The Wegovy website also says that adults on average lose about 15% of their body weight or 35 pounds on the medication—and this one is approved for weight loss.
• Tirzepetide (Mounjaro, Zepbound). This medication is a GLP-1/GIP receptor agonist, which essentially means it’s similar to semaglutide but targets an additional receptor in the body (GIP), Dr. Ali explains. These medications include Mounjaro, which is FDA-approved to treat type 2 diabetes, and Zepbound, which is designed for weight loss. The Zepbound website says that people lost up to 48 pounds during a 17-month clinical trial.
• Liraglutide (Saxenda). Sold under the name Saxenda, Liraglutide is a GLP-1 receptor agonist that’s approved for weight loss. Research has found that one out of three people who take Saxenda lost more than 10% of their body weight.

“There are others that are not as well studied and regulated that are sold as supplements,” Dr. Ali says. So be sure to do your research before considering any that are not FDA-approved, and consult your doctor before starting a new weight loss regimen.

Do you need a prescription to get peptides for weight loss?

In order to use peptides that are FDA-approved for weight loss, you need a prescription. There are also some specifics for each drug to indicate if you would be a good candidate.

Zepbound, for example, is designed for people with overweight (which is considered as a BMI of 27 or above) or obesity (a BMI of 30 or above) who also have one or more weight-related conditions like type 2 diabetes, high blood pressure, or high cholesterol. Wegovy also has similar requirements.

Potential side effects of using peptides for weight loss

Every peptide medication for weight loss is different and it’s important to talk to your doctor about the pros and cons of each before deciding on one. However, some common side effects can happen with these medications, and they usually involve the gastrointestinal tract, Dr. Ali says. Those can include:

• Nausea
• Cramping
• Constipation
• Diarrhea

“They tend to be fairly limited and resolve with time,” Dr. Ali says. That’s why the medications are started at a lower dose and ramped up to higher doses with time, he says.

Other potential side effects, per Dr. Buettner, include:

• Low blood sugar
• Injection site reactions like redness, swelling, or pain
• Headache
• Dizziness
• Fatigue

Usually, once your body gets used to the medications, the side effects stop, Dr. Buettner says. But, for some (note: rare) cases, some may experience:

• Gastroparesis
• Pancreatitis
• Changes in vision

If you’re interested in taking a peptide for weight loss, talk to your doctor. They should be able to help guide you through your options.