Mounjaro vs Wegovy: Comparing the weight loss medications

If you're on a weight loss journey, you've likely tried everything from a reduced-calorie diet to intermittent fasting to achieve your goals.

For those who have exhausted their options and still aren't seeing results, weight loss drugs represent a glimmer of hope. When combined with diet and lifestyle changes, these medications can be extremely effective at regulating appetite, restoring metabolism, and ultimately shifting that stubborn weight.

But, with so many different medications now available on the market, it can be difficult to know where to start.

If you've found yourself curious about Mounjaro and Wegovy and are wondering what the difference is, you're in the right place. Read on for everything you need to know about the medications — including how they work, potential side effects and which one is more effective for weight loss.

Note, it's important to see your healthcare provider or use a service like Juniper for official weight loss medication recommendations, as they will assess your suitability based on your personal or family history.

What is Mounjaro?

Mounjaro is a brand name for the active ingredient, tirzepatide. The once-weekly injectable medication was originally developed to improve blood sugar levels in adults with type 2 diabetes, however many patients also noticed it helped greatly with weight reduction.

Mounjaro works similarly to other weight loss medications like Wegovy, in that it mimics gut hormones called incretins, which signal the pancreas to release insulin after eating [1].

However, Mounjaro belongs to a different class of medications called dual GIP/GLP-1 agonists — meaning that it uses 2 digestive hormones, GLP-1 and GIP (instead of just GLP-1), to regulate glucose and register feelings of fullness in the brain [2].

What is Wegovy?

Wegovy is an injectable medication that is used for weight loss and weight management for those considered overweight or obese.

It's manufactured by the same company that makes Ozempic, Novo Nordisk, but although both medications are brand names for semaglutide, there are important differences.

Firstly, Wegovy is specifically designed for chronic weight management, while Ozempic is licensed as a diabetes medication [3]. And, unlike Mounjaro, Wegovy is a single-action medication that mimics one hormone in the body, GLP-1, to manage blood sugar levels and achieve weight loss.

Are Mounjaro and Wegovy both approved for weight loss?

Yes, both Wegovy and Mounjaro are approved for weight loss. Mounjaro was authorised by the UK's regulation authority for use in weight loss management in 2024 [4].

Meanwhile, Wegovy is specifically indicated for weight loss and was also made available in the UK in 2023 [5]. However, it's important to note that not everyone is eligible for these medications, as they are designed for adults who are obese (BMI over 30) or who have excess weight (BMI over 27).

Which one is more effective for weight loss: Wegovy or Mounjaro?

Both Wegovy and Mounjaro are considered the gold standard when it comes to aiding weight loss efforts. Thus far, the two medications haven't been directly compared to each other in medical trials.

However, existing research shows that Wegovy achieves an average of 15% weight loss an average for patients, compared to 20% weight loss for patients [6].

Here's how the two stack up against each other:

Effectiveness of Wegovy

Wegovy is an incredibly effective weight loss medication. Its efficacy is only compounded by the fact that it's a once-weekly injection, making it easier for patients to remember to take it.

In a series of randomised controlled trials conducted by Novo Nordisk, weight loss was assessed in 1961 adults taking either Wegovy or a placebo for 68 weeks [7].

Both groups were instructed to also follow a reduced-calorie diet and increase their exercise.

The patients saw an average weight loss of 15.9 kg, or about 15% of their body weight compared to 2.7 kilos or 2.5% body weight in the placebo group. In these groups, 83% lost 5% or more of their weight, 66% lost 10% or more, and 48% lost 15% or more.

Effectiveness of Mounjaro

According to clinical trials, GLP-1/GIP treatment is the most effective treatment for weight loss that is available right now.

One study of over 2,500 patients from July 2022 found an average of up to 20.9% body weight loss in patients on GLP-1/GIP after 72 weeks.

In the same study, up to 90.9% of patients were able to achieve at least 5% weight loss, up to 83.5% were able to achieve at least 10% weight loss and 56.7% were able to achieve at least 20% weight loss in 72 weeks of treatment [8].

Is Mounjaro better than Wegovy?

You might look at these results and assume that Mounjaro is the clear winner. It's possible that the slightly favourable results observed in Mounjaro are thanks to 'twincretin' dual-agonist mechanism working more effectively for diabetes management [9].

But, do they work just as effectively in those who don't have underlying issues with processing glucose?

To rule out the mediating effect, an ongoing clinical trial will compare Mounjaro and Wegovy for weight loss in patients without diabetes, with the study expected to be completed in early 2025 [10].

What are the dosing schedules for Mounjaro vs Ozempic?

Mounjaro and Wegovy vary greatly in their dosing amounts and schedules.

For Mounjaro, the starting dose is 2.5 mg once weekly for 4 weeks [11]. Patients usually then increase to 5 mg once weekly for at least 4 weeks. Depending on how your body responds to treatment, your doctor might increase your dose by 2.5 mg every 4 weeks.

For Wegovy, you will likely start on the lowest dosage, which is 0.25 mg once weekly [12]. If your body responds well, your Wegovy dosage will likely increase gradually every 4 weeks until you reach the maintenance dosage of 2.4 mg once per week.

Wegovy vs Mounjaro side effects

Like any medications, both Wegovy and Mounjaro have side effects you should be aware of.

The most common side effects experienced with both medications include [13]:

• Indigestion
• Nausea
• Diarrhoea
• Vomiting
• Constipation
• Stomach pain
• Dizziness
• Heartburn
• Fatigue
• Stomach flu
• Heartburn
• Runny nose
• Sore throat
• Headaches

Another more serious but rare side effect that has been observed with Wegovy is developing thyroid tumours, including cancer. [14]

Before taking either of these weight loss medications, it is important to work with your doctor to rule out underlying health issues that may pose a risk.

Can Mounjaro or Wegovy lead to muscle loss?

We know that both Mounjaro and Wegovy are effective at promoting weight loss, but is that only fat, or does it also include muscle mass?

Well, according to a study in the New England Journal of Medicine, participants on semaglutide (Wegovy) lost a considerable amount of fat but also experienced a reduction in muscle mass [7]. This is likely a result of rapid weight loss.

Tirzepatide (Mounjaro), however, seems to cause less muscle loss [16]. This could be due to its dual action on both GLP-1 and GIP receptors, which might help better preserve lean body mass — though more long-term studies are needed to confirm these effects.

Whichever medication you're prescribed, there are steps you can take to minimise muscle mass loss:

• Increase your protein intake
• Make sure your calorie deficit isn't too extreme
• Add strength training to your fitness routine
• Give your body rest days
• Stay hydrated
• Make sure you're sleeping enough

What are the cost differences?

At Juniper, we can prescribe either Mounjaro or Wegovy, depending on the treatment plan that is more suitable for your needs.

Juniper's Weight Reset Programme ranges from £189 to £299 per month and includes health coaching, nutritional advice, and ongoing support, as well as medication.

Are both medications available in the UK?

Yes, both Wegovy and Mounjaro are available in the UK, and both are medication options in our Weight Reset Programme.

Can you switch from Wegovy to Mounjaro?

As everyone's body is different, it can take a bit of trial and error to find the right weight loss drug for your needs. It is possible to switch from Wegovy to Mounjaro (or vice versa), but they're not interchangeable, meaning you can't use them simultaneously.

It's also recommended that you take a slow and intentional approach with the guidance of your health provider if you're making the switch.

For example, if you're going from Wegovy to Mounjaro, you'd need to start at the lowest dose of the latter and gradually titrate up to higher doses [15]. Be sure to consult your healthcare provider if you have any concerns about side effects or effectiveness before stopping your treatment.

Mounjaro or Wegovy: Which one should you choose?

Both medications are extremely effective for achieving significant weight loss.

At the end of the day, the best option depends on you, your body and your lifestyle. By taking the Juniper quiz, you can check your eligibility for both medications, and kickstart your journey towards a healthier and happier you.

Ready to jump off the diet bandwagon for good? Start your sustainable weight loss journey here.

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