Eli Lilly’s tirzepatide—sold under the brand name Mounjaro® to manage type 2 diabetes—sparked a lot of excitement when researchers announced that patients on the drug lost more than 15% of their body weight during one of the drug’s trials. There’s already the popular GLP-1 drug class, which includes Ozempic®, Wegovy®, and other medications that are being used—sometimes off-label—for weight loss. But recent studies show tirzepatide—the active ingredient Mounjaro and the newly approved Zepbound™—may lead to even better results in weight loss than other drugs on the market right now.
GLP-1 RAs—or glucagon-like peptide-1 receptor agonists—mimic the actions of GLP-1, a natural incretin hormone made predominantly in your lower gut. This hormone slows gastric emptying, meaning you remain fuller longer; it also sends the message to your brain: “I am full; I am satisfied.”
The big question since 2022 has been, “Is Mounjaro approved for weight loss?” And many people have been eagerly hoping for the answer yes.
The short answer is: Mounjaro is not approved for weight loss. However, Mounjaro’s sister drug, Zepbound—also tirzepatide—has just received FDA approval to treat obesity.
After clinical trials found that people with obesity or overweight with comorbidities (but without type 2 diabetes) lost a considerable amount of weight with Mounjaro (tirzepatide), the FDA fast-tracked the drug’s approval process. (The FDA speeds an approval review when the drug or device treats a serious condition and fills an unmet medical need.)
In addition to Zepbound, only six other drugs are approved by the U.S. Food and Drug Administration (FDA) for chronic weight management. Other drugs, including Mounjaro, are prescribed off-label for weight loss.
Now that tirzepatide is FDA-approved for weight reduction, your insurance company may offer coverage to treat obesity, making it more accessible and affordable to those who need it. Right now, people can pay over $1,000 a month out of pocket to use Mounjaro off-label for weight loss.
But between Mounjaro or Zepbound, which is better for weight loss? And why is Mounjaro still prescribed off-label for weight loss if the FDA approved Zepbound? Read on.
Early research on Mounjaro (tirzepatide) showed weight loss results that were even more significant than those for patients on the popular drug Ozempic, which is often used off-label for weight loss. One reason for that: Mounjaro is the first GLP-1/GIP receptor agonist.
Mounjaro differs from the GLP-1 medications used for weight loss that work as receptor agonists. (Agonists activate the same cell receptors as the body's natural chemical messengers.) Mounjaro, a dual agonist, mimics two of the incretin hormones naturally produced in the body that help control blood sugar and regulate appetite: glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP).
By acting on two receptors simultaneously, the results may be more efficient than a GLP-1 RA alone, explains Jennifer Clark, PhD, an expert in obesity science and the former senior research manager for clinical research and strategy at Found. “When combined, the idea is that they will be stronger together,” she explains. Like semaglutide (part of the drug class of medications that targets GLP-1 receptors), tirzepatide slows stomach emptying, which results in feeling fuller for longer while inhibiting the brain’s hunger signals, thus suppressing your appetite.
In 2022, an American Diabetes Association symposium presentedthe results of a double-blind, placebo-controlled study looking at tirzepatide and weight loss among those who did not have type 2 diabetes. The findings showed dramatic weight loss in participants with excess weight and at least one weight-related condition—or obesity. Some lost as much as 22.5% of their body weight after 72 weeks on the drug. This “substantial and sustained” weight loss rivals the effectiveness of weight loss surgery.
And there’s more: The results of a 72-week double-blind, placebo-controlled clinical trial published in the journal The Lancet found that about half the participants (with both obesity and type 2 diabetes) lost approximately 15% of their body weight while taking tirzepatide (Mounjaro).
While these findings are exciting, it’s important to remember that Mounjaro doesn’t work on everyone. In the same way that your body responds to some medications but not others, it may not respond to Mounjaro. That’s why at Found we prioritize tailoring a medication plan to your unique biology. Our clinicians use MetabolicPrint™, a proprietary metabolic health assessment, to identify your body’s biological needs and match you with the proper medication.
When blood sugar levels are high, your body releases insulin. This essential hormone helps blood sugar enter the body’s cells to be used for energy. It also signals the liver to store blood sugar for later use. But if too much sugar enters the bloodstream persistently, things can go awry.
This recurring added sugar intake can lead to higher blood pressure, weight gain, inflammation, and fatty liver disease. Mounjaro helps the body regulate blood sugar levels and reduces the liver’s sugar production and release.
Another result? Mounjaro also helps curb appetite and slows down how quickly the food leaves your stomach, helping you feel fuller longer.
Of course, no medication comes without potential side effects, and that includes tirzepatide.
Most commonly, people taking Mounjaro, Zepbound, or GLP-1s like Ozempic or Wegovy may experience nausea, vomiting, diarrhea, and acid reflux. More serious and less common side effects include pancreatitis, gallbladder disease, and worsening of diabetic eye disease.
It’s important to note that people with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasias should not use Mounjaro or GLP-1s. Find more detailed information about specific medications’ side effects and risks on our dedicated medication page.
In a word, yes. Just because Mounjaro isn’t FDA-approved for chronic weight management like Zepbound doesn’t mean it cannot be prescribed for that condition. This practice, known as off-label prescribing, is both legal and common. In fact, one in five prescriptions is written for off-label use.
Off-label use of a medication is when it’s prescribed for an indication or at a different dose or dosage form that wasn’t covered under the FDA’s original approval. So while Mounjaro is approved to treat type 2 diabetes, health care professionals may also prescribe it off-label to treat excess weight. However, with Zepbound now approved for long-term weight management, and the fact that the Mounjaro savings coupon expired at the end of 2023, time will tell if Mounjaro continues to be prescribed off-label for obesity and overweight.
For all the hype around weight loss with Mounjaro, it doesn’t work for everyone. By understanding the root causes of your weight loss challenges using your MetabolicPrint profile, Found’s obesity-trained clinicians can personalize an approach to your weight management plan. For some, that may mean a non-GLP-1 drug; for others, GLP-1 medications may be a better choice.
Prescriptions for these weight management drugs, and others, are available as part of Found’s weight-loss program when medically appropriate. If a medication isn’t appropriate or if your health insurance plan requires you to try another treatment first—a practice known as step therapy—Found-affiliated providers are trained in obesity medicine and will work with you to determine the medication that is right for you.
Medication, combined with diet and exercise, can help you build and develop healthy habits that will sustain you on your weight journey without feeling deprived. It can be hard to change habits, but having support along the way can help you navigate these changes for the long term. At Found, that support includes 1:1 health coaching, consultations with a board-certified clinician trained in obesity medicine, an app offering a behavior change program, as well as a supportive community.
To discover your MetabolicPrint and start your journey with Found, take our quiz. Found is among the largest medically supported weight care clinics in the country, having served more than 200,000 members to date.
GLP-1 and tirzepatide prescriptions, filled through your local pharmacy, are now available as part of Found's weight-loss toolkit. While these medications can be effective for weight loss, they are not clinically appropriate for everyone. Eligibility for these drugs is based on a thorough evaluation of your medical history and lab work. If GLP-1s or tirzepatide are not appropriate for you, our providers will work with you to determine an effective medication for your health profile.