Widespread shortages of popular weight loss drugs have made headlines in 2023. These headlines have raised awareness within the general public as to the potential efficacy of certain medications in reducing weight. However, several agents are on the market with demonstrated efficacy, some with approved weight loss indications and some without. As a consumer and patient, it is important to understand the differences between popular weight loss medications in order to make informed decisions about one’s plan of care. This article will explore the similarities and differences between two drugs that can help manage weight: Mounjaro and Wegovy.
Mounjaro (tirzepatide) is an injectable medication produced by Eli Lilly. It was first approved in 2022 by the FDA for the treatment of adults with type II diabetes mellitus (T2DM). It is indicated in T2DM patients in combination with diet and exercise to improve blood glucose levels in the body.
Mounjaro works as a glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist. Both GIP and GLP-1 are the body’s natural incretin hormones. It is the first FDA-approved medication that combines these two mechanisms of action into a single molecule.
Its efficacy and safety in this population was demonstrated in phase three SURPASS clinical studies, where Mounjaro improved A1C levels in diabetic patients.
One of the many benefits of Mounjaro is that it can help with weight loss. As aforementioned, Mounjaro mimics the body’s natural incretin hormones: GIP and GLP-1. Incretins are hormones your body releases after eating a meal. They have several effects, including creating satiety (feelings of fullness) by delaying gastric emptying.
Incretin hormones are important to maintaining weight, specifically in overweight and obese individuals. Studies demonstrate that the incretin hormones in overweight or obese individuals may not work as well as they do in individuals of a healthy weight. These abnormalities can occur in those that experience weight fluctuations by gaining weight and losing weight frequently due to dieting.
The phase 3 SURPASS trials that led to Mounjaro’s approval included weight reductions as a key secondary endpoint. Weight loss outcomes were as follows:
A key limitation to using Mounjaro for weight loss is that it is not currently FDA-approved to decrease weight. However, robust results from clinical trials show that it is efficacious in reducing weight.
Additionally, Mounjaro can cause several side effects and has restrictions to its use. Common adverse events include decreased appetite, nausea, vomiting, diarrhea, constipation, stomach pain, and indigestion2. Other more serious adverse events include:
Wegovy (semaglutide) is a once weekly injection. It was approved by the FDA in 2021 for weight management in obese or overweight adults with at least one weight-related issue (e.g., T2DM, high blood pressure, or high cholesterol) in combination with diet and exercise. It is for use specifically in those with a body mass index (BMI) of 27 kg/m2 or more with a weight-related condition or in those with a BMI of 30 kg/m2. Wegovy works by acting like the GLP-1 hormone, regulating appetite and food consumption as a result.
Investigators studied Wegovy’s effects on weight and other endpoints in four 68-week trials, amounting to over 2,600 patients receiving Wegovy over the course of all clinical trials. The biggest study included participants without diabetes with an average weight of 231 pounds and an average BMI of 38 kg/m2. Study results demonstrated that those on Wegovy had an average reduction of 12.4 percent of their baseline body weight compared to those taking placebo. In a separate trial analyzing patients with T2DM, Wegovy patients lost 6.2 percent of their baseline weight versus placebo4.
Limitations
Like with any drug, Wegovy can cause several side effects. These include GI effects such as nausea, vomiting, diarrhea, constipation, indigestion, gas, gastroesophageal reflux disease (GERD), and stomach pain. Other side effects include drowsiness, headache, dizziness, low blood sugar, and gastroenteritis (an intestinal infection).
Additionally, Wegovy’s prescribing information also has warnings for pancreatitis, gallbladder and kidney problems, low blood sugar, and suicidal thoughts.
With the established efficacy in weight loss for both Wegovy and Mounjaro, you may be wondering which is best to help achieve your weight loss goals. However, it is difficult to compare these two medications as there are no controlled head-to-head trials comparing their effects.
Although there are no head-to-head trials comparing Mounjaro to Wegovy, there was a trial comparing Mounjaro to Ozempic. Both Wegovy and Ozempic contain the same drug (semaglutide) but in different doses. Wegovy is administered at a dose of 2.4 mg, while Ozempic is administered at a dose of 0.5 to 1 mg5,6.
In the study comparing Mounjaro to semaglutide (1 mg), Mounjaro lowered patient weight by an average of 17 pounds (5 mg), 21 pounds (10 mg), and 25 pounds (15 mg) versus 13 pounds with semaglutide. Likewise, Mounjaro may be more effective than a 1 mg dose of semaglutide1.
Side Effects
Both Wegovy and Mounjaro have similar side effect profiles, with the majority being GI-related (e.g., nausea, vomiting, and diarrhea). Additionally, they have similar warnings and precautions included in their label for things such as pancreas, gallbladder, and kidney problems.
Cost
A month of treatment with Mounjaro costs around $975, whereas a month of treatment with Wegovy costs around $1,400. These costs may vary depending on your insurance. However, insurance may not cover Mounjaro for the purpose of weight loss as it is not approved for weight loss7.
Conclusion
Wegovy and Mounjaro are both effective options for weight loss, but key differences may make one a better option than the other. Talk with your healthcare provider to see if one of these medications might be right for you.
