Can Tirzepatide (Mounjaro, Zepbound) Help You Lose Weight?
Key takeaways:
Tirzepatide (Mounjaro) is FDA approved for Type 2 diabetes. People taking it tend to lose weight. In November 2023, the FDA approved tirzepatide for weight loss in people without diabetes under the brand name Zepbound.
Tirzepatide is the first medication in its class and comes as a once-weekly injection. It works by impacting your body’s insulin levels, blood glucose (sugar) production, and hunger hormones.
In clinical trials, people without diabetes lost an average of 34 lbs to 48 lbs after taking the highest dose of Zepbound for 72 weeks (16.5 months).
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There’s a newer medication that can help people who are considered obese or overweight: tirzepatide. Under the brand name Mounjaro, this injectable medication is FDA approved for treating Type 2 diabetes. And in November 2023, it also earned FDA approval for chronic weight management in adults — with or without diabetes — under the brand name Zepbound.
When paired with diet and exercise, tirzepatide can both lower blood glucose (sugar) levels and lead to significant weight loss in people with diabetes. And it has been shown to cause weight loss in people without diabetes, too.
If you’re considering tirzepatide for weight loss, reviewing possible side effects, its effectiveness, and whether you meet the requirements is a good place to start.
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What is tirzepatide (Mounjaro, Zepbound)?
Tirzepatide is a newer medication that was initially FDA approved in May 2022 to treat Type 2 diabetes in adults. It’s a once-weekly injection. When used along with a diabetes-friendly diet and regular exercise, it can help lower blood glucose levels. In addition to treating Type 2 diabetes, tirzepatide is also approved for weight loss in adults, under the brand name Zepbound.
How does tirzepatide cause weight loss?
Tirzepatide is thought to promote weight loss by decreasing your appetite and prolonging feelings of fullness. That’s because these effects can cause you to eat fewer calories.
Tirzepatide is unique because it’s the first combination of two classes of medications: a glucagon-like peptide-1 (GLP-1) receptor agonist and a glucose-dependent insulinotropic polypeptide (GIP) receptor agonist. Therefore, tirzepatide is known as a dual GLP-1/GIP receptor agonist.
GLP-1 and GIP are both incretin hormones, which are hormones that are released after eating. Tirzepatide works by mimicking their effects. This includes telling the pancreas to release insulin after eating and signaling the liver to lower the amount of glucose it’s making. These effects help lower blood glucose.
In addition to helping lower blood glucose, tirzepatide helps with weight loss in a couple ways:
It signals to the brain that you’re full — so you eat less.
It slows the movement of food through your stomach — so you feel full longer.
Other similar injectable weight loss medications only mimic one incretin — GLP-1. It’s thought that because tirzepatide acts like two incretins, it can cause more weight loss than current alternatives. Researchers have studied how effective tirzepatide is for weight loss — for people with and without diabetes.
How much weight do you typically lose on tirzepatide?
While everyone’s experience is unique, many people have lost 15% or more of their starting body weight with tirzepatide.
A clinical trial of over 2,500 people who are considered obese or overweight experienced significant weight loss in the first of tirzepatide’s weight loss studies. Those treated with tirzepatide had an average weight loss of 15% to 20% of their starting body weight over 72 weeks (about 16.5 months). This worked out to an average weight loss of 34 lbs to 48 lbs. Those taking the placebo (an injection with no medication in it) only had an average of 3% weight loss.
What’s more, over a third of those taking the highest tirzepatide dose (15 mg per week) lost at least 25% of their starting body weight (over 58 lbs).
Can you take tirzepatide for weight loss?
Yes, tirzepatide is FDA approved for chronic weight management in adults. But there are certain requirements recommended by the manufacturer. You may qualify for tirzepatide for weight loss if:
You have a body mass index (BMI) of at least 30
You have a BMI of at least 27 and you have one or more weight-related health conditions, such as diabetes, sleep apnea, or high cholesterol
If you don’t meet these BMI criteria, it’s possible a healthcare provider may still prescribe tirzepatide for weight loss. But this would be considered an off-label use of the medication.
What are the side effects of tirzepatide?
Like any medication, tirzepatide can cause side effects. These seem to be most bothersome when first starting it or after raising the dose. Most side effects are mild and resolve with time.
Common side effects include:
Nausea
Vomiting
Diarrhea
Loss of appetite
Stomach pain
Constipation
Upset stomach
If these side effects are severe or ongoing, discuss them with your healthcare provider.
What are the dangers of using tirzepatide for weight loss?
There are also some potentially serious side effects that can happen with tirzepatide. These include:
Severe allergic reaction: This can cause a rash and breathing difficulties, and requires immediate medical attention.
Pancreatitis (swelling of the pancreas): This can cause severe stomach or back pain, vomiting, and fevers, and requires immediate medical attention.
Thyroid cancer: Your healthcare provider may recommend avoiding tirzepatide if you or a close family member has a history of certain types of thyroid cancer.
Gallbladder problems: This can include gallstones.
Hypoglycemia (low blood glucose): This may be more likely to happen if you also take insulin, sulfonylureas, or glinides for Type 2 diabetes.
Tirzepatide can also interact with other medications. Make sure you review your medications with your healthcare provider and pharmacist.
What are the best alternatives to tirzepatide for weight loss?
If tirzepatide for weight loss isn’t right for you, the good news is that there are other medication options. The right treatment for you will depend on many factors, including your medical history and personal preferences.
Other medications that can help with weight loss include:
Semaglutide (Wegovy)
Liraglutide (Saxenda)
Orlistat (Alli, Xenical)
Naltrexone / bupropion (Contrave)
Phentermine / topiramate (Qsymia)
Phentermine (Adipex-P)
The bottom line
Tirzepatide (Mounjaro, Zepbound) is a weekly injection that can help lower blood glucose (sugar) for people with Type 2 diabetes. It’s also FDA approved for chronic weight management in adults with or without diabetes. Along with diet and exercise, tirzepatide can lead to significant weight loss — an average of 15% to 20% (34 lbs to 48 lbs). But tirzepatide for weight loss is only recommended for people who meet certain BMI criteria.
Tirzepatide signals to your brain that you’re full, slows down digestion, and lowers blood glucose. It may be one of many possible weight loss options. But it may not be right for everyone. Be sure to talk with your healthcare provider about which option is best for you.
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References
Chavda, V. P., et al. (2022). Tirzepatide, a new era of dual-targeted treatment for diabetes and obesity: A mini-review. Molecules.
Eli Lilly and Company. (2022). Lilly receives U.S. FDA Fast Track designation for tirzepatide for the treatment of adults with obesity, or overweight with weight-related comorbidities.
Eli Lilly and Company. (2023). FDA approves Lilly's Zepbound™ (tirzepatide) for chronic weight management, a powerful new option for the treatment of obesity or overweight with weight-related medical problems.
Eli Lilly and Company. (2023). Mounjaro [package insert].
Eli Lilly and Company. (2023). Zepbound [package insert].
Jastreboff, A. M., et al. (2022). Tirzepatide once weekly for the treatment of obesity. The New England Journal of Medicine.
Nauck, M. A., et al. (2018). Incretin hormones: Their role in health and disease. Diabetes, Obesity and Metabolism.
U.S. Food and Drug Administration. (2023). FDA approves new medication for chronic weight management.
