If you’re among the roughly 50% of Americans who are actively trying to lose weight, you’re likely aware of the growing popularity of injectable Type 2 Diabetes medications known as GLP-1 receptor agonists as weight loss treatments. While some GLP-1 receptor agonists, such as Wegovy (semaglutide) and Saxenda (liraglutide), have been FDA-approved for chronic weight management (after extensive clinical trials demonstrated their effectiveness for weight loss in obese and overweight populations, including for individuals without Type 2 Diabetes), many others are prescribed off-label for weight loss purposes. (An off-label prescription is any prescription written by a doctor for a purpose other than the one(s) a medication is approved for.)
Eli Lilly manufactures two injectable anti-diabetic medications known as Trulicity (dulaglutide) and Mounjaro (tirzepatide), both of which are FDA-approved for the treatment of Type 2 Diabetes Mellitus. But can these medications also be used for weight loss? And, if so, is one more effective than the other?
Below, we’ll explore Trulicity and Mounjaro in more detail. We’ll consider how each drug works, its side effects and drug interactions, and what is known about its weight loss potential. By the end of this article, you should be ready to speak with your doctor about both drug options and discuss their pros and cons. Your doctor will be able to support you in achieving your weight loss goals and help you determine which weight loss medication (if any) will be the best fit for your particular needs and circumstances.
What Is Mounjaro?
Mounjaro is a prescription, name-brand medication with the active ingredient tirzepatide. It is indicated for the treatment of Type 2 Diabetes in adults over the age of 18 and helps to control blood sugar levels in combination with regular exercise and a healthy diet. Mounjaro has been associated with weight loss in clinical trials but is not currently approved as a weight loss drug. It comes in pre-filled, single-use pens and is injected once weekly under the skin of the thigh, upper arm, or abdomen.
Mounjaro is the first (and currently only) dual-agonist drug on the market. It targets GLP-1 and GIP receptors in the body, which is one of the primary characteristics that sets it apart from Trulicity (more on this below).
What Is Trulicity?
Trulicity is a name-brand prescription medication with the active ingredient dulaglutide. It is indicated for the treatment of Type 2 Diabetes in individuals over the age of 10 and is also approved for the reduction of major adverse cardiovascular events in patients with Type 2 Diabetes and established heart disease. Like Mounjaro, Trulicity is not currently approved as a weight loss drug. It comes in pre-filled, injectable pens and is administered subcutaneously into the upper arm, abdomen, or thigh.
Trulicity is a GLP-1 receptor agonist. This class of drugs mimics the incretin hormone glucagon-like peptide 1, which helps manage blood glucose levels in response to food intake (more on this below).
Trulicity vs. Mounjaro for Weight Loss
It may seem counterintuitive that a medication intended to treat Type 2 Diabetes can also promote weight loss. But when we take a closer look, we see that digestion, appetite, and blood glucose levels are actually very much intertwined. Put on your science hat because we’re going to take a short dive into some of the fundamentals of body chemistry and consider how Mounjaro and Trulicity impact them:
How Does Mounjaro Help for Weight Loss
Let’s start with the basics. When you consume food (sugars), your body starts the digestive process, which involves a variety of different reactions. One of these is the release of two hormones, known as incretin hormones, in your small intestine. These two hormones are called glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP). They bind to receptor sites throughout the body and trigger a variety of metabolic responses including:
- The stimulation of insulin secretion in the pancreas
- The reduction of glucagon secretion in the liver
As blood sugar levels become controlled by the processes mentioned above, GLP-1 and GIP also communicate that digestion is underway to other body systems. This results in other physical responses like:
- The slowing of gastric emptying (the rate at which food leaves the stomach)
- The decrease in hunger
Mounjaro is a dual-action drug that imitates both GLP-1 and GIP and binds to their respective receptors throughout the body. It reduces blood glucose levels and also helps suppress appetite and diminish cravings, which can lead to weight loss. Mounjaro is most effective in combination with healthy lifestyle changes (reduced calorie diet and exercise).
See also: Trulicity vs Ozempic
How Does Trulicity Help for Weight Loss?
Trulicity’s mechanism of action is very similar to Mounjaro’s, except that Trulicity only mimics one incretin hormone—GLP-1—instead of two. Like other GLP-1 receptor agonist drugs, it controls blood sugar levels, reduces appetite, slows down digestion, helps diminish cravings, and increases feelings of satiety (fullness), all of which can contribute to weight loss. Trulicity is also most effective when paired with ongoing healthy lifestyle changes.
Trulicity vs. Mounjaro: Application Methods
Trulicity and Mounjaro are both administered by once-weekly subcutaneous injection. Your doctor will demonstrate how to properly inject your medication, and you can always contact your pharmacist or refer to the package insert that comes with your drug for more information. Always administer medications exactly as instructed by your healthcare provider.
In general, both Trulicity and Mounjaro are administered as follows:
- On the same day each week, at any time of day, with or without food
- Under the skin of the thigh, abdomen, or upper arm (never into a muscle or vein)
- Never into the same injection site twice in a row
- With properly cleaned hands and attention to the expiration date, appearance, and dose of the drug
- With proper and safe disposal of the pen/needle after the dose has been administered (use of an FDA-cleared sharps disposal container recommended)
Consult Trulicity’s website and Mounjaro’s website for more information about injecting these drugs.
In terms of dosing, both Trulicity and Mounjaro are first prescribed at a low starting dose, which may be increased by your doctor at 4-week intervals until a higher maintenance dose is reached. Your doctor will typically stop increasing either drug’s dose at the lowest possible dose that is effective for your treatment goals.
Trulicity is available in the following doses:
- 0.75 mg
- 1.5 mg
- 3 mg
- 4.5 mg
Mounjaro is available in the following doses:
- 7.5 mg
- 10 mg
- 12.5 mg
- 15 mg
Are These Medications FDA-Approved?
Yes, Mounjaro and Trulicity are both FDA-approved, but not for weight loss. That being said, tirzepatide was recently approved for weight loss and chronic weight management under the brand name Zepbound. Zepbound should be available to Americans before the end of 2023.
Currently, Trulicity is approved for:
- The treatment of Type 2 Diabetes Mellitus in patients over 10 years old
- The reduction of risk associated with major adverse cardiovascular events in patients with Type 2 Diabetes and diagnosed heart disease
Currently, Mounjaro is approved for:
- The treatment of Type 2 Diabetes in adult patients over the age of 18
Currently, Zepbound is approved for:
- Chronic weight management in adults who are obese (BMI over 30) or overweight (BMI over 27) with at least one weight-related medical condition such as high blood pressure, heart disease, or high cholesterol
How Much Weight Do People Lose on Trulicity and Mounjaro?
Now, here’s the information you’ve been really waiting for. How do Trulicity and Mounjaro measure up against each other when it comes to weight loss? Let’s take a look at the research:
A research study published in 2020 found that Type 2 Diabetes patients taking a 1.5 mg dose of dulaglutide lost an average of approximately 7 pounds after 6 months. Another study found that patients taking higher doses of the drug (3 mg or 4 mg) lost closer to 9 or 10 pounds after 9 months on the drug.
While these results are notable and demonstrate that Trulicity can positively impact weight loss, Mounjaro’s reported weight loss results in clinical trials are quite a bit more impressive.
In a large study published in 2022, more than 2,500 obese and overweight adults were given weekly tirzepatide injections of 5 mg, 10 mg, or 15 mg for 72 weeks, including a 20-week dose-escalation period. More than 85% of patients reduced their weight by 5% or more, and in the group of patients that received the highest doses, the mean body weight reduction from starting weight was almost 21%. In other words, patients taking weekly 15 mg Mounjaro injections lost one-fifth of their weight in under a year and a half!
Side Effects of Mounjaro and Trulicity
Both Mounjaro and Trulicity have similar side effects, the most common being gastrointestinal issues that often resolve over time as your body adjusts to each drug.
Common side effects of Trulicity and Mounjaro include:
- Nausea, diarrhea, constipation, vomiting, abdominal pain, indigestion, decreased appetite
- Tiredness, dizziness, headache
- Injection site reactions
More serious side effects can include:
- Serious allergic reactions
- Severe low blood sugar (especially in combination with other anti-diabetic medications)
- Severe digestive problems
- Gallbladder, pancreas, or kidney problems
- Vision changes
- The development of thyroid tumors
Your doctor may not recommend Trulicity or Mounjaro for you if:
- You are pregnant, breastfeeding, or trying to become pregnant
- You have a personal or family history of certain types of thyroid cancer
- You have Type 1 Diabetes
- You have a history of digestive problems, pancreatitis, kidney disease, gallbladder issues, or diabetic retinopathy
Drug Interactions
Before starting Mounjaro or Trulicity, be sure to disclose all medications you are currently taking to your doctor, including over-the-counter drugs and natural or herbal supplements and vitamins. Both drugs may interact negatively with a variety of other medications, causing potentially serious outcomes. In particular, Trulicity and Mounjaro’s impact on oral medications and other anti-diabetic drugs should be carefully considered.
The Verdict
In the end, it’s pretty clear that—at least when it comes to weight loss outcomes—Mounjaro is the winner. Though Mounjaro is not (yet) approved as a weight loss drug, results from clinical trials appear to be extremely promising.
If you are interested in trying Mounjaro or Trulicity for weight loss, speak with your doctor or healthcare provider about an off-label prescription. After considering your medical history and weight loss goals, they’ll be able to tell you whether or not one of these drugs may be the right choice for you.
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About the Author
Ida Edlweiss Gumpal is a licensed Pharmacist and medical writer. She took her internships at Mercury Drug Corporation, Inc., a Hospital internship at De Vera Medical Center, Inc., and a Manufacturing internship at Philmed Laboratories, Inc. She has plans on attending medical school with the goal of specializing in Neurosurgery or Cardiothoracic surgery.