Wondering if Mounjaro could be the key to your weight loss journey? This article explores how the medication works, its benefits, and what to consider before starting.

Mounjaro dose pens

Key facts

  • Mounjaro was initially approved for type 2 diabetes management. In November 2023, its active ingredient, tirzepatide, was FDA-approved under the brand name Zepbound as a weight-loss medication.
  • Clinical trials have shown significant weight loss in participants using Mounjaro. The most significant weight loss was observed in those on the highest dose (15 mg weekly) compared to placebo and other diabetes medications.
  • It is available in doses of 2.5 mg, 5 mg, 10 mg, and 15 mg, with the maximum dose being 15 mg taken once weekly.
  • Common side effects of Mounjaro and Zepbound include nausea, diarrhea, decreased appetite, and weight loss.
  • Serious side effects can occur, such as pancreatitis, severe low blood sugar, gallbladder disease, and an increased risk of thyroid cancer.

Table of Contents

What is Mounjaro?

Mounjaro is the first medicine in a drug class known as GIP/GLP-1 receptor agonists. It is FDA-approved to improve blood sugar control in people with type 2 diabetes along with a healthy diet and exercise. 

Can Mounjaro help you lose weight?

Yes. And in fact, the FDA approved a drug called Zepbound for weight loss based on clinical research supporting this outcome. (Zepbound is the same medicine as Mounjaro at the same strength, but with a different name for use as a weight-loss treatment.)

The FDA’s approval of the medicine was based primarily on the results from two trials. 

Both studies evaluated the drug’s effectiveness for weight loss and maintenance along with a reduced-calorie diet and an increase in physical activity in overweight or obese adults with at least one weight-related condition.

The trials looked at the results after 72 weeks of taking the medicine at doses of either 5 mg, 10 mg, or 15 mg once weekly. At the end of the study period, participants who had received any dose of the medication lost a significant amount of weight compared to those who had received a placebo (inactive treatment).

How much weight will you lose taking Mounjaro/Zepbound?

The larger of the trials enrolled adults without diabetes. The starting average body weight was 231 pounds (105 kilograms) and the average body-mass index (BMI, a measure of weight relative to height) was 38. Those who received 15 mg, the highest approved dose, lost an average of 18% of their body weight compared to those taking a placebo.

For the second trial, in adults with type 2 diabetes, the starting average body weight was 222 pounds (101 kilograms), with an average BMI of 36. At the end of the trial, those taking 15 milligrams of the medicine lost an average of 12% of their body weight compared to those taking a placebo.

Who should not take this medication?

You should only take these medicines if your doctor has prescribed them for you. 

Mounjaro is FDA-approved to treat people with type 2 diabetes. Zepbound is approved to treat adults with obesity (a BMI of 30 or more) or overweight (a BMI of 27 or more) with at least one weight-related condition (such as type 2 diabetes, high blood pressure, or high cholesterol).

Mounjaro is not FDA-approved for people with type 1 diabetes, but your doctor may suggest using it off-label (in a manner not officially approved by the FDA) if you’re dealing with high blood sugar levels and low insulin sensitivity. 

Learn more in: Can You Take Mounjaro If You Have Type 1 Diabetes?

Neither drug is recommended for people who are pregnant. You will have to speak with your healthcare provider and stop the medication if you are pregnant or trying to become pregnant. 

Do not use either medicine if you or any of your family members have ever had medullary thyroid carcinoma (MTC), or if you have Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). 

Do not use Mounjaro or Zepbound if you are allergic to tirzepatide or any of the other ingredients in the medications.

Tell your doctor all medications that you use before starting treatment with either of these drugs.

See the prescribing information for Mounjaro and Zepbound for full information about who should use and avoid these medications.

Learn about potential side effects in: Mounjaro Side Effects.

Can you take Mounjaro or Zepbound and other medications at the same time?

This will depend on what other medications you’re taking. 

Generally speaking, you can take Mounjaro and Zepbound with medications like metformin and/or insulin, if you’ve been prescribed all of the medications concurrently. Always inform your healthcare provider about all of the medicines you’re taking. 

You should not combine Mounjaro with GLP-1 medications. GLP-1 receptor agonists include:

Mounjaro should also not be combined with DPP-4 inhibitors. These include:

  • Sitagliptin (Januvia)
  • Saxagliptin (Onglyza)
  • Linagliptin (Tradjenta)
  • Alogliptin (Nesina)

Always talk with your doctor if you’re unsure of how any medications you take will interact with any new medications you’re considering taking. 

How much do you take for weight loss?

There is no recommended dose for weight loss because Mounjaro isn’t explicitly approved for weight loss by the FDA. 

For Zepbound, available doses are 2.5 mg, 5 mg, 10 mg, and 15 mg taken by injection once weekly, with 15 mg being the maximum dose.

Talk with your doctor if you want to lose weight. In addition to Zepbound, there are other diabetes treatments specifically approved by the FDA for weight loss. 

 Read more: Mounjaro Dosing Guide.

How long does it take to lose weight on Mounjaro?

Taking Mounjaro’s weight-loss counterpart, Zepbound, will not be successful overnight. 

Any weight loss experienced while taking Zepbound will also require lifestyle changes, such as modifying your diet and increasing physical activity.

Studies looking at the efficacy of Zepbound for weight loss have been conducted over many months, with the trials used as the basis for the FDA approval lasting nearly a year and a half. 

Why am I not losing weight on Mounjaro or Zepbound?

If you are not losing weight when taking this medication, there are a number of possible common culprits. 

You may have simply hit a weight-loss plateau as your body slows its metabolism and adjusts to a new set point. Over time, you may begin to lose weight again.

You may not be taking the recommended dose, or you may not have made sufficient changes to your lifestyle to help support the weight loss promoted by the medication. 

And for some people, the drug may simply not be an effective tool for weight loss and management. Not every medicine will work for every person.

Is Ozempic or Mounjaro better for weight loss?

Ozempic and Mounjaro’s weight-loss counterpart Zepound both function similarly and can help with weight loss.

Although Ozempic is not FDA-approved as a weight-loss drug, both medicines suppress appetite and slow digestion. 

Additionally, both medications help to stabilize blood sugar levels — which causes many people to lose weight while taking either one.

However, recent research shows that Mounajaro/Zepbound causes more weight loss than Ozempic in people who are obese.  

The average trial participant lost 12 pounds more when taking Mounjaro/Zepbound than Ozempic at the maximum weekly dosage of 15 mg. 

Learn more about how these medications compare in: Ozempic vs. Mounjaro: Which One Should You Choose?

Can I take Mounjaro or Zepbound if I don’t have diabetes? 

Mounjaro is only FDA-approved for people with type 2 diabetes. Zepbound, however, is approved in overweight or obese adults with at least one weight-related condition.

Additionally, many medications for blood sugar control and weight loss are prescribed by physicians off-label.

If your doctor has determined that you are a candidate for Mounjaro, they may prescribe you the medication off-label to treat conditions like:

Never take a medication that is not prescribed for you, and talk to your doctor before starting any medication.