What is Mounjaro?

Mounjaro (tirzepatide) is a once-weekly injectable medication that helps lower blood glucose levels. It’s much like popular GLP-1 medications such as the diabetes medication Ozempic® or the weight-loss drug Wegovy®, manufactured by competitor Novo Nordisk. However, Mounjaro is in a drug class all its own because it’s a dual-targeted treatment.

It’s currently indicated for those patients with type 2 diabetes, but health care professionals can prescribe Mounjaro for weight loss off-label. For best weight loss results, Mounjaro should accompany healthy lifestyle changes—like diet and physical activity.

Although it’s not an obesity drug, Mounjaro (tirzepatide) just received a “fast track designation” from the FDA for treating overweight and obesity. When the FDA fast-tracks a drug, it means the regulators expedite the review of the drug because it treats a serious condition and has an “unmet need.” So, Mounjaro may soon not only be FDA approved as a diabetes medication but as a new weight-loss drug as well.

Why are obesity doctors excited about Mounjaro weight loss?

The findings of a clinical trial on tirzepatide weight loss showed that participants dropped up to 22.5% of their total body weight. Those are impressive stats, given that people taking many existing FDA-approved medications for obesity usually lose 5% to 15% of their total body weight.

Eli Lilly released preliminary results from its SURMOUNT-1 clinical trial in April 2022. Participants with obesity or those with excess weight – a body mass index (BMI) of 27 or greater—who had at least one other comorbidity (but not diabetes) had weight reductions of up to 52 pounds during the 72-week Mounjaro weight-loss trial.

Mounjaro weight loss varied by dose. Study participants on a 5 mg dose of tirzepatide for weight loss experienced an average weight loss of 35 pounds or 16% of their body weight. Those on a 10 mg dose lost an average of 49 pounds or 21.4% of their body weight.

On the highest dose—15 mg—people on tirzepatide lost an average of 52 pounds or 22.5% of their body weight. On the other hand, the placebo group lost just five pounds or 2.4% of their body weight over that same amount of time.

The randomized, double-blind tirzepatide weight-loss clinical trial included 2,539 participants throughout the U.S., Argentina, Brazil, China, India, Japan, Mexico, Russia, and Taiwan, with a mean baseline body weight of 231 pounds. All those randomly placed in the Mounjaro (tirzepatide) study began with a 2.5 mg weekly dose. They then underwent a dose-escalation period that increased by 2.5 mg every four weeks until they reached a target dose of 5, 10, or 15 mg.

While the FDA approved Mounjaro (tirzepatide) to treat type 2 diabetes, doctors specializing in obesity are particularly excited about this medication given the preliminary SURMOUNT-1 results.

“As a board-certified obesity specialist, I believe that Mounjaro (tirzepatide) has the potential to be a game-changer in the treatment of obesity for certain patients who may not have responded to other medicines,” says Found’s chief of Medical Affairs Rekha Kumar, MD, MS. “A medication with this efficacy gives hope to patients who have run out of existing medication options because the mechanism of Mounjaro (tirzepatide) is unique. We are excited about the possibility of adding Mounjaro (tirzepatide) to the broad toolkit of medications Found clinicians already use to provide the best care possible to each Found member.”

How does Mounjaro work for weight loss?

As mentioned above, Mounjaro works much like other meds in the GLP-1 class, but it has the additional benefit of acting on not just one hormone but two. So, unlike its predecessors, which have been very effective but only mimic one hormone, Mounjaro acts on two incretin hormones, which can make it more effective.

In their April 2022 press release, Eli Lilly explained why this dual mechanism is so important. They detailed that the GIP hormone receptor agonist complements the GLP-1 hormone receptor agonist in a novel way. In addition, the release noted that obesity “is a chronic, progressive disease caused by disruptions in the mechanisms that control body weight, often leading to an increase in food intake and/or a decrease in energy expenditure.”

The release said, “GIP has been shown to decrease food intake and increase energy expenditure, resulting in weight reductions, and when combined with GLP-1 receptor agonism, may result in greater effects on markers of metabolic dysregulation such as body weight, glucose and lipids.” Meaning the incretin hormones work together to help maintain weight loss by regulating blood glucose levels or appetite and helping your body lose more body fat.

BUT WHAT ARE INCRETIN HORMONES?

After eating, your gut naturally releases incretin hormones—the two primary hormones are GIP and GLP-1. These hormones help regulate the insulin the pancreas releases to keep blood sugar levels under control effectively. But those who have overweight or obesity can become insulin resistant—meaning their body doesn’t respond to the hormone’s signaling—which results in too much glucose in the blood. Insulin resistance can lead to type 2 diabetes, weight gain, and elevated blood sugar levels.

More than that, the GLP-1 incretin hormone helps food digestion happen more slowly, often called gastric or stomach emptying, causing you to feel fuller longer.

What is the Mounjaro dose for weight loss?

Health care professionals recommend all patients begin their Mounjaro weight loss journey at 2.5 mg to see how well their body tolerates it and then increase the dose from there. It’s essential to follow your health care provider's instructions.

Here is Mounjaro’s recommended dosing schedule:

First four weeks: 2.5 mg weekly

Second four weeks: 5 mg once weekly

Third four weeks: 7.5 mg once weekly

Fourth four weeks: 10 mg once weekly

Fifth four weeks: 12.5 mg once weekly

Sixth four weeks: 15 mg once weekly (maximum dose)

How could Mounjaro (tirzepatide) help you lose weight?

Like similar GLP-1 medications, Mounjaro (tirzepatide) is an injectable medication used once weekly that aids in controlling blood sugar levels that may also support weight loss.

GLP-1 receptor agonists seem to aid in weight loss in two key ways. First, they cause the stomach to empty more slowly, so you feel satisfied with less food. This slowing helps reduce caloric intake. Second, the GLP-1 receptor agonists appear to reduce appetite and hunger, which can help you make nutritional choices that better align with your goals.

The biological changes from GLP-1 medications may also help reduce your set point weight—the weight your body strives to maintain due to hormones, biology, and surroundings. Tirzepatide, like GLP-1 medications used for weight loss—sometimes off-label—such as Ozempic, Saxenda®, Trulicity®, Rybelsus®, Wegovy®, and Victoza®, may help you lose weight and keep it off long-term.

The novel thing about tirzepatide is it also works on GIP receptors. When you eat food, the GIP hormone stimulates insulin. But when your blood sugar falls, they stimulate glucagon secretion. Controlling these processes can help support weight loss beyond what GLP-1 medications and lifestyle changes alone can do.

What are the tirzepatide side effects?

The most common side effects of Mounjaro (tirzepatide) are:

• constipation
• decreased appetite
• diarrhea
• indigestion
• nausea
• stomach pain
• vomiting

Like most GLP-1 receptor agonists, tirzepatide has an FDA-mandated boxed—or black box—warning for patients with a personal or family history of medullary thyroid cancer or who have multiple endocrine neoplasia syndrome type 2. They should not take tirzepatide for weight loss or other treatments.

How much does Mounjaro cost?

Because Mounjaro is so new, many insurance companies don’t cover it yet. According to Lilly’s list price, Mounjaro costs $1,023.04 per four-week fill. Lilly note, “the amount you pay will largely depend on your prescription drug insurance plan.”

That means that one 28-day fill will be upward of $1,000 without insurance. Check with your insurance company to see if they cover Mounjaro.