Not losing weight on Mounjaro? 8 reasons why

Key Points

• There may be many reasons why you're not losing weight on Mounjaro, including medication dose, diet, physical activity, emotional eating triggers, sleep, stress, other drugs, and more
• Weight loss plateaus are normal; the scale doesn't always tell the whole story
• Diabetes drugs like Mounjaro work better when paired with a healthy diet and moderate exercise
• A registered dietitian can provide a custom, personalized weight loss diet plan

Mounjaro (tirzepatide) helps many people lose weight and manage type 2 diabetes. But "many" doesn't mean "all." 

If your scale isn't moving, you're not alone, and you're not doing something wrong.

Let's dig into the reasons why Mounjaro might not be delivering the results you hoped for. Plus, nationally-recognized Registered Dietitian Lyla Joffe, MS, RD, offers expert advice on what to do when you're not losing weight on Mounjaro.

What is Mounjaro (tirzepatide)?

Mounjaro is a medication authorized by the US FDA for adults with type 2 diabetes.

When used together with diet and exercise, it helps improve blood sugar (glucose) control in people living with insulin resistance.

Mounjaro is not approved for weight loss, but its main ingredient, tirzepatide, is approved for weight loss under the name Zepbound.

So, if you're not losing weight while taking Mounjaro, don't lose hope. A few adjustments may be needed to your medication, lifestyle, or expectations to help get things moving.

Here's why weight loss results with Mounjaro can vary.

How does Mounjaro work?

Tirzepatide works by mimicking two important hormones in your body, GLP-1 and GIP.

These hormones control your hunger signals, how quickly you digest food, and how your body manages blood sugar.

Clinical studies show that Mounjaro reduces appetite and promotes a sense of fullness, leading people to eat several hundred fewer calories at meals.

Here's how these hormones help:

• GLP-1 (Glucagon-like Peptide-1): Slows digestion, reduces appetite, and helps the body produce insulin
• GIP (Glucose-Dependent Insulinotropic Polypeptide): Improves how the body processes sugar and works with GLP-1 to support blood sugar control

Learning how Mounjaro affects the body is necessary, but let’s look at what results you might expect.

How much weight can you lose on Mounjaro?

Mounjaro is not approved for weight loss, but people taking it often lose weight. In a study of over 2,500 adults with obesity or overweight, higher doses of tirzepatide led to 15% to 21% body weight loss in a little over a year (18 months).

For someone starting at 200 lbs, that's a 30-40 lb weight loss.

However, even in clinical studies, results vary.

“Just like the weight did not come on overnight, neither will it come off overnight. A healthy rate of weight loss is 1-2 pounds per week,” says Lyla Joffe, RD, Registered Dietitian.

Weight loss varies from person to person

About 15% of people taking Mounjaro lose less than 5% of their body weight. If you are in this group, it does not mean you are doing something wrong. Some bodies simply respond differently. Your doctor may suggest adjusting your dose, trying a different medication, or addressing underlying factors.

If you're taking Mounjaro or another diabetes weight loss drug, you might be hoping to see some weight loss along with better blood sugar control.

While weight loss is possible, it's important to set realistic expectations.

Achieving sustainable weight loss

Registered Dietitian Lyla Joffe, RD, says, "Sustainable weight loss is not achieved overnight. If we lose weight too quickly, we risk nutrient deficiency, bone density loss, and muscle wasting. Although weight loss is a fair goal, the ultimate goal is to be healthy. Just like the weight did not come on overnight, neither will it come off overnight. A healthy rate of weight loss is 1-2 pounds per week, and the journey isn't always a straight line. Stay patient and consistent with your lifestyle changes, and you will reach your goals."

If you are not seeing expected results, several factors could be at play.

What to expect: The Mounjaro weight loss timeline

Weight loss is subjective and varies by person. Also, body weight naturally fluctuates 2 to 4 pounds daily due to water retention and sodium intake. Weekly or monthly trends provide a more accurate picture than daily measurements.

However, let’s look at the results from the clinical trial SURMOUNT-1 to get an idea of how Mounjaro (tirzepatide) works over time.

• Starting out (Weeks 1-4): Mounjaro starts at 2.5 mg once weekly. This initial amount helps the body adjust, and it is not designed for major weight loss
• Dose increases (Weeks 5-20): A healthcare provider typically increases the dose by 2.5 mg every 4 weeks until it reaches the maintenance level. Most people may notice changes in appetite and gradual weight loss during this time
• The 12-week checkpoint: 82% of participants in the study achieved at least 5% weight reduction by this milestone
• Peak results (72 weeks): The most substantial weight loss appeared around 17 months. Participants experienced 16% to 22% weight reduction. Those on the highest dose (15 mg) lost more than those on lower doses (5 mg or 10 mg).

Note: The SURMOUNT-1 tirzepatide weight loss results come from participants without type 2 diabetes. In a different trial (SURMOUNT-2), people with type 2 diabetes lost weight more gradually. They averaged a 13% to 15% reduction over the same timeframe.

8 reasons why you're not losing weight on Mounjaro

Registered Dietitian Joffe, RD, says, “Weight loss is multi-faceted…In order to be successful, we must look at the journey holistically.”

1. Diet still matters

While Mounjaro helps lower your appetite, what you eat remains essential for weight loss.

Clinical trials confirm that people on tirzepatide achieved better results when combining the medication with healthy lifestyle changes.

“Weight loss is multifaceted. Sleep, stress & exercise impact the secretion of hunger hormones and dictate our cravings. In order to be successful, we must look at the journey holistically,” says Joffe, RD. “Instead of opting for crash diets, think about changes you can sustain lifelong. When it comes to nutrition, it is all about quality over quantity. If a diet is rich in processed foods, they will not be efficiently metabolized and can encourage inflammation. Focus on single-ingredient whole foods to decrease inflammation and increase satiety.”

Foods to avoid

Ultraprocessed foods, sugary items, and large portions can work against Mounjaro's appetite-suppressing effects. 

Foods high in added sugars, saturated fats, and sodium are calorie-dense, which means they pack more calories into smaller portions. This makes it easier to consume excess calories even when you feel less hungry on Mounjaro.

Additionally, restaurant meals often contain hidden calories from cooking oils and butter, even in seemingly healthy options.

Foods to eat

• Protein when included in meals: Aim for 2-3 ounces per serving (about the size of the palm of your hand), according to the American Heart Association (AHA)
• Fiber-rich vegetables: Fill half your plate with non-starchy veggies like broccoli, spinach, peppers, or zucchini
• Whole grains: Choose brown rice, quinoa, or whole wheat bread over white/refined options
• Healthy fats: Add avocado, olive oil, nuts, or seeds in moderation

🌱 Plant-based protein sources include lentils, chickpeas, tofu, and tempeh. A cup of cooked lentils has about 18 grams of protein.

💡 Tip: Consider prepping meals on Sundays to make it easier to eat nutritious food throughout the week. The Mediterranean diet is a great place to start for a nutritious eating plan.

Consider working with a weight loss dietitian to get a personalized Mounjaro diet plan that supports your health goals.

2. Emotional eating triggers

Using food to cope with emotions is more common than you might think. Whether it's reaching for ice cream after a stressful day or snacking on chips when you're bored, many of us turn to food for comfort.

There's nothing wrong with enjoying a variety of foods. However, if strong urges to eat non-nutritious foods become roadblocks to your health goals, don't get disheartened.

Fighting food cravings or “food noise” is not a weakness. These thoughts are complex biological triggers shaped by years of disordered eating patterns, stress responses, and brain chemistry.

Ways to delay emotional eating urges in the short-term

• Physically moving away from the trigger food (when possible)
• Going for a walk
• Calling a friend
• Try mindful eating by putting your fork down between bites without scrolling on your phone
• Writing in a journal (or a notes app on your phone) about how your cravings make you feel when you do not give in to them
• Evaluate what the cravings do for you (do they help with boredom, are they a “treat” for getting through the day, or are they a way to “wind down” or “relax”?)

Getting help

If emotional eating or binge eating affects your progress despite your best efforts, consider working with a mental health counselor. They can help you develop strategies to manage your emotions without relying on food.

3. Lack of physical activity

Exercise plays an important role, even when you're taking Mounjaro or other GLP-1 drugs. The medication may help control your appetite, but regular physical activity is also needed.

Physical activity doesn't have to mean intense workouts; even moderate activities like brisk walking make a difference.

💡Tip: The US CDC recommends 150 minutes of moderate exercise each week, which breaks down to 30 minutes a day, five days a week. Please consult your healthcare provider before starting any new exercise regimen.

Strength training

When you lose weight, you can lose muscle along with fat. This slows your metabolism and makes it harder to keep losing weight. Strength training helps you hold onto muscle while burning fat.

Aim for:

• At least 2 strength training sessions per week (CDC)
• 20-30 minutes per session

💡 Tip: Some people prefer starting with resistance bands if weights feel intimidating. They are an inexpensive way to get started.

4. Mounjaro takes time to work

Mounjaro takes time to reach its full effect in your system. Your body needs an adjustment period, just as it does with any new treatment.

What to expect in the first few months

In the first couple of months on Mounjaro, together with a nutritious diet and regular exercise, you may notice some changes in your weight. However, weight loss differs from person to person.

Also, even if you lose weight initially, you may encounter another common experience later on: weight loss plateaus.

What if you hit a weight loss plateau?

Anyone trying to lose weight will likely hit a weight loss plateau. This is when weight loss slows or temporarily stops despite being on weight loss medication and having healthy habits.

Research shows weight loss plateaus are common and affect most dieters.

Why does this happen? There may be many reasons for a weight loss plateau. One reason is that the body does not like sudden or drastic changes. It is wired to try to regain balance when it senses the risk of starvation. These changes can slow or temporarily halt weight loss.

This response may have evolved as a survival mechanism. When the body senses lower energy intake, it triggers compensatory changes, including increased appetite and reduced calorie burning.

Weight loss also reduces muscle mass along with fat. This process may slow down metabolism and make it harder to lose weight.

💡 Tip: Some people find it helpful to set a weekly reminder for their injection day. Taking Mounjaro around the same time each week can help maintain steady medication levels in the body. Talk with your healthcare provider about the best injection schedule for your routine.

Hitting a weight loss plateau on Mounjaro does not necessarily mean the medication has stopped working. Please talk to your doctor and consider working with a registered dietitian to support your health goals.

5. Find your optimal dose

In a tirzepatide clinical trial, participants taking 5 mg lost about 16% of their starting weight, while those on 10 mg lost 21%, and people on 15 mg lost 22.5%. For someone starting at 200 pounds, that means losing 32 pounds or 45 pounds.

Starting dose: Doctors typically start people on a low dose of 2.5 mg weekly to help the body adjust and reduce side effects. Over time, they may increase the dose gradually based on how the body responds to the medication.

Please note: Dosage changes should always be discussed with a healthcare provider who can evaluate the adjustment while monitoring for safety.

6. Effect of other medications on weight loss

If you're not seeing expected results with Mounjaro, other prescriptions or health conditions might be contributing.

Blood pressure drugs, antidepressants, antipsychotics, and hormonal therapies can all affect weight loss response. Sometimes, minor adjustments to when you take other prescription medications or to their dosage can help overcome a weight loss plateau.

Please note: Please do not abruptly stop taking Mounjaro or any other current prescriptions. Discuss your concerns with a healthcare provider before changing any of your prescription medications or dosage.

7. Poor sleep and chronic stress

Sleep deprivation and chronic stress can undermine weight loss efforts.

When you don't get enough sleep, your body produces more ghrelin (the hunger hormone) and less leptin (the fullness hormone). This hormonal shift may increase feelings of hunger throughout the day, making it harder to stick to your eating goals.

Chronic stress raises cortisol (a stress hormone), which can increase hunger and weight gain, particularly belly fat. These factors could make weight loss more challenging.

Sleep and stress management strategies

Improving sleep quality and managing stress may support your weight loss efforts.

Consider these approaches to getting better sleep and lowering stress:

• Limiting screen time before bed
• Getting 7-9 hours of sleep per night
• Reducing stress through walking, deep breathing, journaling, or chatting with a good friend

💡 Tip: Even 30 minutes of extra sleep can make a difference!

8. Your body may be changing, even if the scale is not

The weighing scale doesn't always share the whole story about your progress.

Muscle is denser than fat and takes up less space in your body. Losing fat while maintaining muscle may keep your weight stable even as your body composition improves.

This is especially common for people new to strength training.

Here are some other ways to track progress

• Track other successes: Measure your waist, hips, and arms each month with a measuring tape*
• Visual motivation: Take progress photos every 2-4 weeks to see how your body is changing
• Notice how your clothes fit: For example, if your pants are a little looser but the scale stays the same, you’re making progress
• Pay attention to your energy levels: Are you feeling more energetic during the day? This could also be a sign that you are making progress towards your health goals
• Caution: If measuring your weight and body results in feelings of anxiety or affects your mental health adversely, please reach out to a mental health counselor first.

Final Thoughts: Losing weight on Mounjaro

Living with type 2 diabetes and managing weight on Mounjaro is different for everyone.

Sustainable results typically come from many factors working together: medication, nutrition, physical activity, sleep, stress management, and overall health. Mounjaro is just a piece of the puzzle.

Weight loss takes time, and progress isn't always linear. Setbacks happen. Focusing on overall health improvements beyond the scale can help you stay on track.

If you're not seeing expected weight loss, talk to your healthcare provider about adjusting your dose or approach. A registered dietitian can also provide personalized nutrition advice for your needs.

Find a registered dietitian to help you lose weight on Mounjaro (tirzepatide), covered by your insurance.

Frequently Asked Questions (FAQs)

How fast can I lose weight on Mounjaro?

Mounjaro is FDA-approved for managing type 2 diabetes, not weight loss. However, weight changes are a common effect of the medication.

Clinical trials showed that combining Mounjaro with diet and exercise led to gradual weight reductions of 15% to 20% over 72 weeks (approximately 17 months). Individual results vary widely based on factors like starting weight, adherence to lifestyle changes, and dose.

Joffe, RD, says, “Work with your healthcare provider to set realistic expectations based on your specific situation and health goals. A healthy rate of weight loss is generally 1-2 pounds per week, creating a more sustainable approach to long-term success.”

Do diet and exercise help Mounjaro work better?

Yes. Combining Mounjaro with structured lifestyle changes leads to greater weight loss than medication alone. In one study, people who completed a 12-week intensive program (low-calorie diet, exercise, weekly counseling) lost about 7% of their body weight before starting Mounjaro. After adding the medication, they reached approximately 24% to 27% total weight loss over time. 

In comparison, people who took Mounjaro with diet and exercise counseling each month lost 15% to 22.5% over the same period.

While you don't need an intensive program before starting, these findings show that structured diet and exercise changes can enhance your results.

How to speed up weight loss on Mounjaro?

While it's natural to want faster results, steady, sustainable changes work best. Research shows that combining Mounjaro with healthy habits is effective.

Consider following a diabetes-friendly diet, such as the Mediterranean diet, with whole vegetables, lean proteins, whole grains, and healthy fats to support weight loss.

Regular activity like walking or exercises you enjoy can make a difference. Consistency matters more than intensity. Take your medication as prescribed, eat regular meals, and maintain daily habits.

Mounjaro vs. Zepbound: What's the difference?

Both Mounjaro and Zepbound contain the same active ingredient (tirzepatide) and are made by Eli Lilly, but they have different FDA-approved uses.

Mounjaro is approved for type 2 diabetes. Zepbound is approved for weight loss in adults with obesity and to treat obstructive sleep apnea.

Both require one weekly injection and work by affecting appetite and digestion. Talk to your healthcare provider about which may be appropriate for your situation.

Start losing weight today. Find a weight loss dietitian who accepts your insurance.

The views expressed by authors and contributors of such content are not endorsed or approved by Fay and are intended for informational purposes only. The content is reviewed by Fay only to confirm educational value and audience interest. You are encouraged to discuss any questions that you may have about your health with a healthcare provider.