Thinking About Trying Mounjaro? Here's What You Can Expect Week by Week
Mounjaro injection pen
Weight loss medications are fully mainstream, with celebrities touting their benefits and even Costco jumping in on their popularity. Right now, Mounjaro is in higher demand than ever.
Let's be clear: Diet culture as a whole is a real problem, these meds are administered under the supervision and guidance of physicians—making them a lot more credible in terms of their efficacy and safety than, say, the flat-tummy teas and detoxes influencers shill on Instagram. Weight loss medications, when taken properly and under the instruction of a doctor, are a game changer for those who need them.
That said, there are important things to know about Mounjaro and its sister drug, Zepbound.
"Currently in the United States, Mounjaro (tirzepetide) is only indicated for Type 2 diabetics," Los Angeles-based obesity doctor Dr. Sulagna Misra, MD, BCMAS, tells Parade. "Currently, Zepbound (the new form of Mounjaro or tirzepetide) is used for obesity, which means a body mass index of equal to 27 or higher with two co-morbid obesity-related conditions like Type 2 diabetes, cardiovascular diseases, hypertension, obstructive sleep apnea and/or others. It can also be prescribed for individuals with a BMI of equal to or greater than 30."
That said, a lot of celebrities who've publicly espoused the benefits of Mounjaro and ZepBbound haven't appeared, at least superficially, to be obese, though we obviously don't know all of their medical histories.
"Anti-obesity medications are not 'vanity drugs meant for people of normal weight to lose five pounds," Dr. Katherine H. Saunders, MD, DABOM, an internist with New York-Presbyterian Hospital says. "They are medical treatments for the disease of obesity. Zepbound is a powerful medication that has many potential risks if not prescribed or taken appropriately. Before starting Zepbound, it’s critical to have a healthcare provider or ideally a care team who practices evidence-based medical weight management. It’s the Wild West out there right now with inappropriate prescribing and prescribing without education or support."
Other individuals specifically should avoid Mounjaro, Zepbound or other tirzepetide medications.
"Mounjaro falls into the category of medications known as GLP1 agonists," Jewel Osborne-Wu, MD, a physician at Revolution Med, explains. Those with a family history of medullary thyroid cancer, a family history of multiple endocrine neoplasia 2, a personal history of pancreatitis or a Type 1 diabetes diagnosis will want to steer clear of these medications—or at least have a very honest conversation with their medical care team.
Dr. Osborne-Wu also notes, "There is not any current evidence that supports the use of these medications in pregnancy, so for women seeking to become pregnant or are already pregnant, they shouldn't take Mounjaro."
Phew, not that we have all that out of the way, if you do get a Mounjaro or Zepbound prescription, here's what you can expect week by week of your treatment.
Related: Stars Who've Opened Up About Using Weight Loss Drugs
What To Expect From Taking Mounjaro Week by Week
Week 1
Like most things, Mounjaro and Zepbound will start low and slow for most patients, according to Dr. Osborne-Wu.
"Mounjaro is always started at a dose of 2.5 mg, unless a patient is being switched from another GLP1 agonist such as Ozempic (in which case their provider will describe the dose conversion as appropriate)," she explains. "This is the lowest dose and patient experiences vary in terms of weight loss results. It is often not the most effective dose so most patients will require dose escalation over time."
"Zepbound starts to work in your body within hours of the first injection—some notice the feeling of fullness right away, others notice it as the days go on," Dr. Angela Fitch MD, FACP, FOMA, Dipl. ABOM, president of the Obesity Medicine Association and chief medical officer at knownwell, tells us.
Despite the low dose, you may see some side effects at this time, most commonly mild nausea and constipation—and Dr. Osborne-Wu says not to worry too much, because they typically subside over time as you get used to the medication. You can alleviate them somewhat by staying hydrated and, if needed, popping a fiber supplement to keep your bowel movements regular.
According to New York City obesity doctor Dr. Sue Decotiis, MD, some patients may also experience vomiting or acid reflux in their early weeks of Mounjaro or Zepbound treatment. Like Dr. Osborne-Wu, she recommends drinking a lot of water to prevent or at least minimize side effects.
"Some people will need almost a gallon a day. If patients are dehydrated, they are not going to burn fat, they’ll burn muscle and gain the weight back when they’re off the drugs," Dr. Decotiis warns.
Related: What Is Ozempic Face?
Weeks 2 - 4
According to Dr. Fitch, your second week of Zepbound or Mounjaro treatment will be somewhat similar to your first.
"Nausea and digestive discomfort can persist into the second week, as they last anywhere from a few days to a few months depending on the person and things like their diet and hydration levels," she notes. "You will not feel as good or be as successful if you just take medication and don't eat."
Related: How Much Weight Can You Expect to Lose on Ozempic?
Week 5
This is often when patients begin to see results, but that can vary depending on your specific course of treatment.
"It depends on the dosage," Dr. Decotiis explains. "Some people may need a much higher dose. I tend to feel that the lower two doses can be effective for those who don’t have that much weight to lose or for young people. They might see very good results in the first or second month, but heavier patients may need a much higher dosage for four or five months to really start noticing significant fat loss."
Related: Thinking About Trying Ozempic? Here's What You Can Expect Week by Week
Week 6 and Beyond
According to Dr. Fitch, you should see results by now to some degree.
"Some notice significant weight loss in the first few weeks, others the second, third or fourth month of usage. I always tell my patients not to get frustrated if they don't see results right away," Dr. Fitch advises. "Ideally, we’d like to see 5% weight loss by 12 weeks, but for some people, it may require a much higher dosage and for others, it may require more of a focus on healthy lifestyle habits."
Dr. Saunders notes that some patients may plateau after the sixth week of Mounjaro or Zepbound treatment, especially if their dosage doesn't increase.
"Plateaus don't happen because the medication stops working, but because someone's body is fighting back. This is a process called metabolic adaptation," Dr. Saunders says. "If a plateau happens before health goals are achieved, the care team can assess the situation and decide on next steps."
Those next steps likely won't involve cutting your Mounjaro or Zepbound, because they're designed for long-term use and may cause patients to gain the weight back (or even more weight) when they stop using them.
"Anti-obesity medications like Zepbound should not be used for short-term weight loss, but rather long-term treatment of obesity, which is a chronic disease requiring lifelong intervention," Dr. Saunders reminds us. "We prepare patients to be on an anti-obesity medication (or some type of medical obesity treatment) long-term for their chronic disease, which is only controlled for the duration of time they’re treated. Stopping Zepbound or another anti-obesity medication is a setup for weight regain (which can be sudden or insidious) for most individuals. Weight-related health complications that had been controlled on an anti-obesity medication may no longer be controlled when the medication is stopped."
Next, What Happens When You Stop Taking Ozempic?
