Weightloss, Weightloss Medications

In 2023, shortage of popular weight loss drugs has sparked interest in the potential of certain medications for weight management. Consumers and patients must understand these medications to make informed choices on their weight loss journey. This article delves into the similarities and distinctions between two such drugs: Mounjaro and Wegovy.


Mounjaro, also known as tirzepatide, is an injectable medication developed by Eli Lilly. Initially, it received FDA approval in 2022 for the treatment of adults suffering from type II diabetes mellitus (T2DM). Its primary indication is to be used alongside diet and exercise to enhance blood glucose control in T2DM patients.

Mechanism of Action:

Mounjaro operates as both a glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist. These hormones are natural incretins produced by the body. Notably, Mounjaro is the first FDA-approved medication to combine both mechanisms within a single molecule.


One significant advantage of Mounjaro is its potential to aid in weight loss. As it mimics the body’s natural incretin hormones, GIP and GLP-1, it influences feelings of fullness by delaying gastric emptying, thus aiding in weight management. In individuals who are overweight or obese, incretin hormones may not function optimally, making Mounjaro a promising option.

Clinical trials conducted during the phase three SURPASS studies, which led to Mounjaro’s approval, showed promising weight loss outcomes:

  • In SURPASS-1, Mounjaro led to an average weight loss of 14 pounds (5 mg), 15 pounds (10 mg), and 17 pounds (15 mg), compared to 2 pounds with a placebo 1.
  • In SURPASS-2, Mounjaro resulted in weight reductions of 17 pounds (5 mg), 21 pounds (10 mg), and 25 pounds (15 mg) compared to 13 pounds with semaglutide 1.
  • In SURPASS-3, Mounjaro led to weight reductions of 15 pounds (5 mg), 21 pounds (10 mg), and 25 pounds (15 mg) compared to a weight gain of 4 pounds with insulin degludec 1.
  • In SURPASS-4, Mounjaro resulted in weight reductions of 14 pounds (5 mg), 20 pounds (10 mg), and 23 pounds (15 mg) compared to a gain of 4 pounds with insulin glargine 1.
  • In SURPASS-5, Mounjaro led to weight reductions of 12 pounds (5 mg), 17 pounds (10 mg), and 19 pounds (15 mg) compared to a gain of 4 pounds with a placebo1.


A key limitation of Mounjaro for weight loss is its lack of FDA approval specifically for weight reduction, despite robust clinical trial results demonstrating its efficacy in this regard. Additionally, Mounjaro comes with potential side effects and usage restrictions, including decreased appetite, nausea, vomiting, diarrhea, constipation, stomach pain, and indigestion. More severe adverse events encompass pancreatitis, dangerously low blood sugar when used with insulin, acute kidney injury, allergic reactions, gastrointestinal (GI) disorders, and acute gallbladder disease 2.


Wegovy, containing semaglutide, is a once-weekly injection. It received FDA approval in 2021 for weight management in obese or overweight adults who have at least one weight-related condition, such as T2DM, high blood pressure, or high cholesterol. It is specifically intended for those with a body mass index (BMI) of 27 kg/m² or more with a weight-related condition or a BMI of 30 kg/m².


Wegovy’s effects on weight and related endpoints were evaluated in four 68-week trials involving over 2,600 patients. The largest study involved individuals without diabetes, who had an average weight of 231 pounds and an average BMI of 38 kg/m². The results showcased a remarkable average reduction of 12.4 percent of baseline body weight in those taking Wegovy compared to those on a placebo 4. In a separate trial involving patients with T2DM, Wegovy users experienced a 6.2 percent reduction in baseline weight compared to placebo 4.


Like any medication, Wegovy has its share of side effects. User may experience gastrointestinal issues like nausea, vomiting, diarrhea, constipation, indigestion, gas, and gastroesophageal reflux disease (GERD). Symptoms like drowsiness, headache, dizziness, low blood sugar, and gastroenteritis (intestinal infection) are also seen. Wegovy’s prescribing information also carries warnings for pancreatitis, gallbladder and kidney problems, low blood sugar, and the potential for inducing suicidal thoughts 5.


Comparing Wegovy and Mounjaro is tricky without direct head-to-head trials, though both aid weight loss effectively. However, a study comparing Mounjaro to semaglutide (1 mg) – the active ingredient in Wegovy – indicated that Mounjaro may be more effective in reducing weight.


In this trial, Mounjaro led to an average weight loss of 17 pounds (5 mg), 21 pounds (10 mg), and 25 pounds (15 mg) compared to 13 pounds with semaglutide (1 mg) 1.

Side Effects:

Both medications share similar side effect profiles, predominantly gastrointestinal, with warnings regarding pancreatitis, gallbladder, and kidney problems 2,5.


Mounjaro costs approximately $975 per month, while Wegovy is priced around $1,400 per month. Insurance coverage may vary, but Mounjaro may not be covered for weight loss purposes due to its lack of FDA approval in this context 7.


Wegovy and Mounjaro present viable options for weight management, each with its own set of advantages and limitations. Consult your healthcare provider to to find the best medication for your weight loss goals.


Eli Lilly and Company. “FDA Approves Lilly’s Mounjaro™ (Tirzepatide Injection), the First and Only Dual GIP and GLP-1 Receptor Agonist for the Treatment of Type 2 Diabetes.”

Eli Lilly and Company. Mounjaro US Prescribing Information.

U.S. Food and Drug Administration. “FDA Approves New Drug for Treatment of Chronic Weight Management as First in 2014.”

U.S. Food and Drug Administration. Wegovy US Prescribing Information.

NiceRx. “Mounjaro vs Wegovy – Cost, Side Effects, Efficacy, Dosage, Uses & Interactions.”