What are Mounjaro and Wegovy?
Mounjaro and Wegovy contain drugs that mimic two hormones in the body that lower hunger: GLP-1 and GIP.
The GLP-1 hormone has three major effects in your body:
- It slows the rate of food movement from your stomach to your small intestine
- It communicates with the appetite control centre in your brain to increase satiety so you feel less hungry
- It manages the release of the insulin and glucagon hormones in your body, ultimately leading to lower blood sugar levels (generally a good thing)
The natural GLP-1 hormone in your body lasts only a few minutes, whereas the GLP-1 drugs can last for many days. This means they can have the above effects over a more sustained period.
Overall, this leads to people feeling less hungry because they have food in their stomachs for longer, and GLP-1’s effect on the brain means that people feel like they have less ‘food noise’ and reduced desires for highly desirable foods.
The main difference between Wegovy and Mounjaro is that the drug in Wegovy mimics a single hormone, GLP-1, while the drug in Mounjaro mimics both GLP-1 and GIP.
GIP is a hormone that supports blood sugar levels and helps our fat cells store more excess energy we might consume in our diets.
This dual-action effect of Mounjaro is thought to explain why better weight-loss results have been seen in the clinical trials published so far.
Mounjaro and Wegovy dosing schedules
The other major difference between Wegovy and Mounjaro is the dosing schedules.
Wegovy has been approved to be delivered at its maximum 2.4 mg dose, which is called its ‘maintenance’ dose.
To reach the maintenance dose level of 2.4 mg, there are four ‘escalation’ doses that you must take over four months to reach the maximum 2.4 mg dose.
It looks like this:
The clinical licensing for Wegovy is clear that it’s mandatory to increase doses each month until the maximum 2.4 mg maintenance dose has been reached.
Mounjaro is slightly different because it has 3 different maintenance doses: 5 mg, 10 mg, and 15 mg.
What this means is that there’s currently more flexibility with the dosing schedules of Mounjaro over Wegovy.
If people feel that they are getting good weight-loss results at a lower maintenance dose of Mounjaro (e.g. 5 mg or 10 mg) then they don’t need to increase their dose further.
Mounjaro also has ‘escalation’ doses, which you’ll be required to take for four weeks if you decide to move up from one maintenance dose to another.
For example, if your current maintenance dose is 5 mg and you want to move up to a 10mg maintenance dose, then you’ll need to spend 4 weeks on the 7.5 mg escalation dose.
If you wanted to go straight up to the maximum 15 mg dose of Mounjaro, this is what your titration plan would look like:
1) How do Wegovy and Mounjaro work?
When we eat food, our gut releases hormones that help the body regulate hunger and blood sugar levels. One of these hormones is GLP-1.
GLP-1 improves insulin function to lower blood sugar levels and delay gastric emptying, decreasing appetite.
GLP-1 also communicates with the brain’s appetite control centre, the hypothalamus, to lower food-seeking behaviour.
Another hormone released from the gut is GIP. GIP helps regulate blood sugar levels and helps our fat cells ‘absorb’ more energy from the bloodstream, which prevents fat from being stored in the liver or pancreas.
GIP also communicates with the brain and is believed to have a similar role to GLP-1 in lowering hunger.
So, both GLP-1 and GIP are hormones released in response to food and signal to the brain to lower hunger and food-seeking behaviours.
However, both hormones are removed from our blood quickly after being released. For example, after two minutes, 50% of the GLP-1 released from the gut in response to a meal is removed from the blood.
This short lifespan means that the effects of GLP-1 and GIP to lower hunger are often short-lived.
How Wegovy works
Wegovy is known as a GLP-1 receptor agonist as it mimics the actions of the hormone GLP-1.
The active ingredient in Wegovy is semaglutide. Semaglutide is about half as potent as the real GLP-1 hormone produced in the gut.
However, semaglutide has been developed to last longer in the blood to provide a sustained effect of lowering hunger to help people eat less and lose weight.
After 4-5 weeks on Wegovy, the semaglutide in the blood reaches a level known as its ‘steady state’. This means its levels will be consistent and stable rather than rising and falling.
How Mounjaro works
Mounjaro is also known as a GLP-1 receptor activator, as it mimics the actions of the hormone GLP-1.
The active ingredient in Mounjaro is tirzepatide. Tirzepatide is about a quarter as potent as the GLP-1 hormone produced by the gut.
However, tirzepatide has the additional function of mimicking the hormone GIP. Because of this additional action, Mounjaro is known as a dual-action GLP-1 and GIP receptor agonist.
Like Wegovy, Mounjaro is a long-acting medication. It takes 4-5 weeks for its active ingredient, tirzepatide, to reach a level in the blood we call its ‘steady state’ where its levels remain consistent and stable in the blood.
Key points:
- GLP-1 and GIP are hormones released by the body after we eat food
- They communicate directly with the brain to lower hunger and food-seeking behaviours
- Wegovy is a single-action weight-loss injection and mimics the actions of the GLP-1 hormone
- Wegovy’s active ingredient is semaglutide and is manufactured by Novo Nordisk
- Mounjaro is a dual-action weight-loss injection and mimics the actions of the hormones GLP-1 and GIP
- Mounjaro’s active ingredient is tirzepatide, and it’s manufactured by Eli Lilly
2) Do you lose more weight on Wegovy or Mounjaro?
Data from randomised controlled trials suggests that Mounjaro leads to more average weight loss than Wegovy.
One study found that Mounjaro supported average weight loss of nearly 25% after one year. So, if you weighed 100kg, that would be a weight loss of 25kg.
In comparison, research on Wegovy suggests it supports an average weight loss of around 16% after one year, 9% less than Mounjaro.
Achieving over 10% weight loss is associated with clinically significant reductions in risk of chronic conditions such as type 2 diabetes and heart disease.
So, research suggests that Mounjaro leads to more average weight loss than Wegovy and may support more people achieving clinically significant weight loss of over 10%.
Key points:
- Research suggests Mounjaro supports more average weight loss after one year
- Average weight loss on Mounjaro after one year is around 25% and 16% on Wegovy
- Research shows more participants achieve more than 10% weight loss on Mounjaro (~90%) than Wegovy (69%)
3) Mounjaro vs Wegovy: Which one should you choose?
Effectiveness
Mounjaro is potentially more effective at supporting obesity and type 2 diabetes than Wegovy.
As demonstrated above, the higher doses of tirzepatide (the active ingredient in Mounjaro) appear to lead to greater weight loss and blood sugar reductions than semaglutide (Wegovy).
However, the two drugs haven’t been compared directly in double-blind, randomised controlled trials (the gold standard of medical research). So, we can’t say for sure which medication will prove more effective.
Additionally, Wegovy appears to have a slightly better safety profile than Mounjaro, with fewer side effects and fewer people stopping the medication due to adverse events.
So, if you were looking at trying GLP-1 medications for weight loss or blood sugar improvements, Mounjaro might be more effective, but you might find you’re more likely to stay on Wegovy.
However, individual medication responses differ significantly, so it’s worth speaking with your healthcare provider to determine what would be best for you.
Side effects and safety
All medications have possible side effects, particularly if you live with other health conditions.
Some will be mild but uncomfortable, such as cramping, and others will be more severe, such as shortness of breath. You must report any side effects you experience to your doctor and healthcare team when on medications.
Tirzepatide seems to be more effective at supporting weight loss than semaglutide but has a poorer safety profile.
In a randomised controlled trial with over 1800 participants comparing tirzepatide to semaglutide, the tirzepatide group reported more serious adverse events (5-7% VS 3%) and higher discontinuation rates due to adverse events (6-8.5% VS 4%).
Additionally, there were more deaths in the Tirzepatide group than semaglutide (12 vs 1). However, the researchers confirmed they didn’t believe these deaths were linked to the medication.
Cost
The cost of Mounjaro and Wegovy is essentially the same, with most providers having the same cost for the lower and highest doses of both medications:
Mounjaro cost
The cost of Mounjaro starts from £229 a month as part of Second Nature’s Mounjaro weight-loss programme for the lowest doses (2.5mg and 5mg), rising to £299 for the highest doses (12.5mg and 15mg).
Wegovy cost
The cost of Second Nature’s Wegovy programme also starts from £229 per month and is designed to match the price of our Mounjaro programme.
Key points:
- Mounjaro is more effective than Wegovy at supporting weight loss and blood sugar reductions
- However, Wegovy seems to lead to fewer side effects and is better tolerated than Mounjaro
- However, individuals will vary in their medication response, so choose the right one for you
- Both medications start from £229 per month with Second Nature
Take home message
Research shows that both Wegovy and Mounjaro lead to significant weight loss. Both medications are also well tolerated, with over 90% of participants who start the drug can stay on it.
However, Mounjaro leads to around 10% more weight loss than Wegovy on average, so Mounjaro is the most effective weight-loss injection available in the UK right now.
Still, everyone responds differently to medications and either Wegovy or Mounjaro can support significant weight loss while you develop the healthy habits needs to maintain the weight loss in the long term.
