With obesity rates continuing to climb in the United States, there has been growing interest in prescription medications that can help with weight loss and weight management. Two such medications that have received a lot of recent attention are Mounjaro and Wegovy.
Mounjaro and Wegovy are both injectable drugs that work by mimicking hormones called incretins. Incretins help regulate blood sugar levels, appetite, and digestion. By acting like naturally-occurring incretin hormones in the body, Mounjaro and Wegovy can promote weight loss in overweight or obese individuals.
While Mounjaro and Wegovy share some similarities, there are also key differences between the two drugs. This comprehensive guide provides an in-depth comparison of Mounjaro vs. Wegovy to help you understand how they are alike and how they differ.
- Wegovy is FDA-approved for chronic weight management, while Mounjaro is approved for type 2 diabetes but often prescribed off-label for weight loss.
- Both medications work by mimicking gut hormones called incretins to reduce appetite and increase feelings of fullness.
- Mounjaro acts on two incretin hormones, GLP-1 and GIP, while Wegovy acts solely on GLP-1.
- Mounjaro seems to result in greater weight loss at maximum doses in clinical trials so far.
- Higher doses of Mounjaro are associated with increased weight loss effects.
- Wegovy and Mounjaro have similar side effect profiles but some different serious risks to monitor.
- Consultation with a healthcare provider is important when considering these medications for weight management.
FDA Approval Status
The first major difference between Mounjaro and Wegovy is their FDA approval status:
- Wegovy is FDA-approved for chronic weight management in adults who are overweight or have obesity. Wegovy received FDA approval for weight management in 2021.
- Mounjaro is FDA-approved to improve blood sugar control in adults with type 2 diabetes, but it is not approved for weight loss. However, Mounjaro is commonly prescribed off-label by doctors for weight loss and weight management.
Mounjaro received FDA approval in 2022 to treat type 2 diabetes. The drug manufacturer has applied for full FDA approval for Mounjaro as a weight loss medication, which was granted on November 8, 2024.
A new version of the popular diabetes treatment Mounjaro can be sold as a weight-loss drug, U.S. regulators announced Wednesday.
The U.S. Food and Drug Administration approved Eli Lilly’s Zepbound, or tirzepatide. The drug helped dieters lose about a quarter of their body weight, or 60 pounds (27 kilograms), in a recent study.
How They Work : Wegovy and Mounjaro
Both Wegovy and Mounjaro work by mimicking hormones called incretins. Incretins are gut hormones released after eating that help regulate blood sugar, appetite, food intake, and digestion.
The two main incretin hormones are:
- GLP-1: Glucagon-like peptide-1
- GIP: Glucose-dependent insulinotropic polypeptide
Wegovy contains the active drug semaglutide, which acts like GLP-1.
Mounjaro contains tripeptide, which is a dual GIP and GLP-1 receptor agonist. This means Mounjaro mimics the effects of both GIP and GLP-1.
By activating GLP-1 and GIP receptors, Mounjaro and Wegovy can:
- Increase insulin production and reduce glucagon secretion to lower blood sugar
- Suppress appetite and promote fullness
- Slow digestion and nutrient absorption
- Enhance metabolism and increase calorie burning
Effectiveness for Weight Loss
Numerous clinical studies have shown that both Mounjaro and Wegovy can produce significant weight loss:
- In trials, Wegovy helped overweight or obese participants lose an average of 12-15% of their body weight over 16-20 months.
- Mounjaro clinical trials found weight loss of up to 20-25 pounds (9-11 kg) with the highest doses over 6 months.
Although Wegovy and Mounjaro haven’t been directly compared in head-to-head studies, existing research suggests Mounjaro produces greater weight loss than Wegovy:
- In trials, the highest dosage of Mounjaro (15 mg) resulted in over 20% body weight loss on average.
- The maximum dosage of Wegovy (2.4 mg) led to approximately 15% body weight reduction on average.
- Mounjaro also lowered HbA1c (a measure of blood sugar control) more than Wegovy in studies.
Experts attribute Mounjaro’s increased weight loss effects to its dual action on both GLP-1 and GIP receptors. Activating both pathways may provide greater effects on body weight and metabolism.
The weight loss effects of Mounjaro also appear to be dose-dependent – higher doses are associated with increased weight loss. Wegovy, on the other hand, only comes in a single maintenance dosage strength.
As injectable incretin mimetics, Mounjaro and Wegovy have some similar side effects:
Common side effects:
- Abdominal pain
- Decreased appetite
These gastrointestinal side effects are most common when starting treatment and often resolve with continued use.
Less common but serious risks:
- Hypoglycemia (low blood sugar)
- Kidney injury
- Severe GI reactions
- Gallbladder disease
- Allergic reactions
- Injection site reactions
Mounjaro may specifically cause:
- Severe nausea and vomiting
- Intestinal obstruction
- Diabetic retinopathy worsening
Wegovy may specifically cause:
- Increased heart rate
- Suicidal thoughts or behavior
- Acute gallbladder disease
- Potential thyroid cancer risk (boxed warning)
Patients should be monitored closely when starting these medications and report any concerning side effects to their healthcare provider. Those with a history of certain medical conditions may not be candidates for Mounjaro or Wegovy treatment.
Administration and Dosage
Mounjaro and Wegovy are both administered by subcutaneous injection once weekly. The drugs are available in pre-filled syringes or pens for self-injection into the abdomen, thigh, or arm.
Wegovy is given at the following doses:
- Weeks 1-4: 0.25 mg
- Weeks 5-8: 0.5 mg
- Weeks 9-12: 1 mg
- Weeks 13-16: 1.7 mg
- Week 17 onward: 2.4 mg (maintenance dose)
Mounjaro starter doses are:
- Weeks 1-4: 2.5 mg
- Weeks 5-8: 5 mg
Maintenance doses can then be increased in 2.5 mg increments up to a maximum of 15 mg once weekly.
The dose of Mounjaro can be individually adjusted based on patient tolerability and weight loss response. Wegovy is only available in set dosage strengths up to 2.4 mg.
Cost and Availability
As brand-name medications, Mounjaro and Wegovy are expensive without insurance:
- Wegovy costs over $1,300 for a one-month supply.
- The monthly cost of Mounjaro is nearly $1,100.
Since Mounjaro is approved to treat diabetes, more insurance plans cover Mounjaro than Wegovy currently. But this may change if Mounjaro receives FDA approval for weight loss.
Manufacturer savings cards can reduce out-of-pocket costs for Mounjaro and Wegovy. Generic forms of the drugs are not available.
In terms of availability, Wegovy has been in shortage supply recently due to high demand. Mounjaro is more readily available but requires prior authorization from most insurance companies when prescribed off-label for weight loss.
Candidates for Treatment
Wegovy and Mounjaro may be appropriate treatment options for individuals with:
- Overweight or obesity (BMI 27 or higher in some cases)
- Type 2 diabetes requiring better blood sugar control
- At least one weight-related health condition, such as high blood pressure, heart disease, or sleep apnea
These medications are generally not recommended for people who:
- Have a history of pancreatitis or severe GI conditions
- Have a personal/family history of certain cancers
- Are pregnant or breastfeeding
- Have severe kidney disease or diabetic retinopathy
- Are on insulin or certain other diabetes medications
Careful screening and monitoring are necessary when using Wegovy or Mounjaro. Treatment may not be suitable for some individuals due to side effect risks or other safety concerns.
Mounjaro vs. Wegovy: Key Differences
- Approved for type 2 diabetes – Approved for chronic weight management
- Common off-label use for weight loss – Given once weekly by injection
- Given once weekly by injection – Dosage increased over 16-20 weeks up to 2.4 mg maintenance dose
- Starting dose 2.5 mg, increased up to 15 mg maximum – Contains semaglutide
- Contains tripeptide – Actives on GLP-1 receptor
- Actives on GLP-1 and GIP receptors – Up to 15% weight loss in studies
- Up to 22% weight loss in studies – Risk of side effects like nausea, vomiting, diarrhea
- Risk of severe nausea, vomiting, diarrhea – Risk of gallbladder disease, pancreatitis, hypoglycemia, kidney injury
- Higher cost without insurance
- Lower cost than Wegovy without insurance
- Currently greater availability than Wegovy
- Expected approval for weight loss in 2023
In patients with obesity and type 2 diabetes needing better blood sugar control, some doctors may prescribe Mounjaro and Wegovy together.
Using both medications simultaneously activates GLP-1 and GIP receptor pathways, which provides synergistic effects on body weight and glucose regulation.
However, combination therapy with Mounjaro and Wegovy has not been well studied. The risks and long-term safety of using both drugs concurrently are unknown.
If combination therapy is being considered, risks and benefits should be carefully weighed under close medical supervision.
Mounjaro vs. Wegovy: Which is Better for Weight Loss?
Based on clinical trial evidence and expert opinion, Mounjaro appears superior to Wegovy for weight loss at the present time.
Potential advantages of Mounjaro over Wegovy include:
- Greater average body weight reduction (up to 22% with Mounjaro compared to 15% with Wegovy)
- Increased weight loss is likely related to its dual mechanism of action on GLP-1 and GIP receptors
- More flexibility in dosing – available in strengths up to 15 mg compared to Wegovy’s single 2.4 mg maintenance dose
- Possibly better tolerability at higher doses
- Lower cost and greater availability currently
However, Wegovy is the only medication specifically approved for chronic weight management. With expected FDA approval, Mounjaro will likely become a leading weight loss medication.
The best choice between Mounjaro and Wegovy depends on individual factors like treatment response, side effects, and insurance coverage. Discussion with a healthcare provider can help determine which medication may be most appropriate.
Weight Loss Results with Mounjaro and Wegovy
In clinical trials, both Mounjaro and Wegovy have demonstrated impressive weight loss capability. Here are some of the results:
Wegovy Weight Loss Results
- Over 2,600 participants involved in Wegovy trials
- 12.4% (27 lb or 12.3 kg) weight loss on average with a 2.4 mg dose
- 26% of patients achieved over 20% body weight loss
- Significant improvements in waist circumference, BMI, and cardiometabolic health
Mounjaro Weight Loss Results
- Nearly 22% (45 lb or 20.5 kg) weight loss with a 15 mg dose of Mounjaro
- Over 25 pounds lost on average at doses of 10 mg and above
- 36-49% of patients had over 15% weight reduction
- Up to 2.5% greater HbA1c reduction compared to Wegovy
- LDL cholesterol decreased 18-22% and triglycerides decreased 12-17%
Clearly, both Wegovy and Mounjaro can provide substantial weight loss in the right candidates. However current evidence indicates Mounjaro may offer greater effects, especially at higher therapeutic doses.
Weight Loss Expectations
If you are considering Mounjaro or Wegovy, it’s important to have realistic expectations about possible weight loss results.
In clinical trials, average weight loss was:
- 15% with Wegovy
- 20-22% with maximum doses of Mounjaro
But individual results can vary significantly based on factors like:
- Dosing regimen
- Medication adherence
- Baseline weight and health status
- Diet and exercise habits
- Genetic and hormonal differences
Some patients may lose 10% of body weight or less, while others may lose 25-30% with these medications when combined with lifestyle intervention.
Gradual and steady weight loss of about 1-2 pounds per week is considered safe and sustainable. Quick weight loss can regain once medication is stopped.
Close medical monitoring and management of expectations is key during treatment. Patience and persistence is required to achieve desired weight loss goals.
Best Candidates for Success
Although Mounjaro and Wegovy can benefit many overweight/obese adults, the best candidates include:
- Individuals with a BMI of 30 or higher, or a BMI of 27-30 with obesity-related medical problems
- Patients highly motivated to make lifestyle changes like improving diet and increasing activity
- Those who have struggled to lose weight or keep it off with other methods
- Patients with obesity and poorly controlled type 2 diabetes needing better blood glucose management
- People willing to adhere closely to prescribed dosing schedules and medical monitoring
- Individuals with realistic expectations of gradual, moderate weight loss for health benefits (not cosmetic weight loss)
- Those who understand possible side effects and are committed to managing them
Engaging in regular doctor visits, tracking progress, modifying behavior, and implementing lifestyle interventions can help promote optimal weight loss success.
Tips for Losing Weight with Mounjaro or Wegovy
If you begin treatment with Mounjaro or Wegovy for weight management, here are some tips that may help maximize your weight loss success:
Follow dosing instructions carefully – Take medication consistently as prescribed. Don’t skip doses. Report concerns to your doctor.
Make dietary changes – Reduce daily calorie intake by 500-600 calories. Limit carbohydrates, fats, and sugars. Increase intake of fruits, vegetables, lean protein, and fiber.
Increase physical activity – Aim for 150-300 minutes per week of moderate exercise like brisk walking. Start slow and increase activity gradually.
Drink plenty of fluids – Stay well hydrated to ease side effects like constipation or diarrhea.
Manage side effects – Report troublesome side effects to your healthcare provider. Take anti-nausea medication if needed.
Monitor progress – Weigh yourself weekly and track food intake. Attend follow-up appointments as scheduled.
Be patient – It may take several months to achieve desired weight loss. Expect plateaus. Stay motivated and consistent.
Following your doctor’s plan along with implementing healthy lifestyle habits can promote the most weight loss and health improvements when using Wegovy or Mounjaro.
Q: Is Mounjaro or Wegovy more effective for weight loss?
A: Early research suggests Mounjaro results in slightly greater weight loss at maximum doses compared to Wegovy. However, comparative studies are still limited.
Q: Is Mounjaro FDA-approved for weight loss?
A: No, currently Mounjaro is only FDA-approved to treat type 2 diabetes. It may be prescribed off-label by doctors for weight management.
Q: What are the most common side effects of Wegovy and Mounjaro?
A: Gastrointestinal symptoms like nausea, vomiting, and diarrhea are most common. Up to 44% of Wegovy users and 33% of Mounjaro users report nausea.
Q: How often are Wegovy and Mounjaro injected?
A: Both medications are injected subcutaneously once weekly at a prescribed dosage strength.
Q: What serious risks do Wegovy and Mounjaro have?
A: Serious risks requiring medical care include pancreatitis, gallbladder disease, kidney injury, and increased heart rate. Both also have a boxed warning for possible thyroid cancer risk.
The Bottom Line
Mounjaro and Wegovy are two of the newest and most promising medications available for managing obesity. Both drugs stimulate GLP-1 receptor activity to suppress appetite, slow digestion, and reduce weight.
Mounjaro also activates the GIP receptor, which may confer enhanced weight lowering effects. Clinical trials have shown excellent efficacy with moderate side effects for both medications.
While currently only approved for diabetes, Mounjaro appears superior to Wegovy for weight loss based on existing data. However, Wegovy will likely remain a mainstay for chronic weight management given its specific FDA approval.
Talk to your doctor to determine if prescription treatment with Wegovy, Mounjaro, or both medications together may be appropriate for your individual health needs and weight loss goals.