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Mounjaro® VS Saxenda®

Robbie Puddick
Written by

Robbie Puddick

Medically reviewed by

Fiona Moncrieff

10 min read
Last updated May 2023

Jump to: What are GLP-1s and GIP? | Mounjaro® and Saxenda® for weight loss and type 2 diabetes | Mounjaro® VS Saxenda®: Which one should I choose? | Take home message

Mounjaro is more effective for weight loss and blood sugar improvements than Saxenda. Mounjaro also appears to have a better safety profile, with fewer people discontinuing the medication due to adverse events and side effects.

So, if you’re looking for a medication to help you lose weight and improve your blood sugar levels, Mounjaro will lead to greater weight loss and blood sugar reductions.

However, individual responses to medications vary between individuals. Be mindful of side effects and contact your healthcare team to determine the appropriate medication and dosage.

What are Mounjaro® and Saxenda®?

Mounjaro and Saxenda are GLP-1 receptor agonists, medications that reduce appetite to support weight loss and improve blood glucose control through various mechanisms.

Mounjaro – in addition to being a GLP-1 medication – is also a glucose-dependent insulinotropic polypeptide (GIP) mimetic.

GIP is a hormone in the body that supports blood glucose levels and helps our fat cells store more excess energy we might consume in our diets.

So, Mounjaro has a dual function that mimics two hormones in the body that support blood glucose levels and weight loss.

Saxenda is manufactured by Novo Nordisk, while Mounjaro is by Eli Lilly. The active ingredient in Mounjaro is tirzepatide and liraglutide in Saxenda.

Mounjaro and Saxenda are approved for individuals living with type 2 diabetes in the U.S.
They were initially approved as prescription drugs but are now widely available online for private purchase.

Saxenda is available in the UK, but Mounjaro is still seeking approval, which is expected towards the end of 2023 or 2024.

A key difference between the medications is the dosing schedules. Mounjaro is injected once a week, while Saxenda is injected once daily.

Dosing schedules:

Not a magic pill

These medications are designed as additional tools for weight management interventions and shouldn’t be considered lifelong medications.

Instead, they should be used to help you kickstart your weight loss and health journey while you commit to living a healthier lifestyle.

At Second Nature, we’ve been trusted by the NHS since 2017 to support people with type 2 diabetes and obesity to lose weight and manage their blood sugar levels and lead healthier lifestyles for the long term.

If you’re considering purchasing Mounjaro (when it’s available in the UK) or Saxenda but need support in making positive changes to your lifestyle, Second Nature could be an option for you.

In 2022, the NHS published data in the BMJ that compared the weight loss outcomes of five providers in the National Diabetes Prevention Programme.

Second Nature was more than twice as effective at supporting weight loss than the other four providers.

Second Nature is launching a new GLP-1 assisted weight loss programme this year. But we have limited space available; register your interest here.

Otherwise, keep reading as we dig into the science of Mounjaro and Saxenda and how GLP-1s work.

1) What are GLP-1 receptor agonists and GIP?

When we eat food, our gut releases a hormone that helps the body regulate hunger and blood sugar levels. This hormone is called GLP-1 (glucagon-like peptide-1).

The actions of GLP-1 are the target of Saxenda and Mounjaro. This class of medications are known as GLP-1 receptor agonists (GLP-1s). They mimic the actions of the hormone GLP-1.

GLP-1s improve insulin function to lower blood sugar levels and delay gastric emptying, decreasing appetite. GLP-1s also communicate with the brain’s appetite control centre, the hypothalamus, to lower food-seeking behaviour.

Additionally, GIP is a hormone also released in response to food and helps to regulate blood sugar levels and helps our fat cells ‘absorb’ more excess energy, which prevents fat from being stored in the liver or pancreas.

The medications that mimic GIP are known as GIP mimetics. These additional actions are the target of Mounjaro, which is a dual-action type 2 diabetes medication.

There are two well-known GLP-1 medications available in the UK and U.S.:

Liraglutide (Saxenda): Taken once a day
Semaglutide (Wegovy and Saxenda): Taken once a week

Currently, there’s only one dual-action GLP-1 and GIP mimetic medication available in the U.S. (not currently available in the UK):

Tirzepatide (Mounjaro): Taken once a week

Do GLP-1 receptor agonists and GIP mimetics work?

Clinical trials have demonstrated that GLP-1s are more effective at weight loss than other weight loss medication drugs like orlistat, which has a different mode of action.

A systematic review and meta-analysis (a study analysing lots of different studies) analysed 28 trials in over 29,000 people investigating the effectiveness of five weight loss medications on weight loss.

The study found that all five medications were more effective than the placebo at supporting weight loss.

This trial included orlistat and the GLP-1 liraglutide and found that liraglutide was more effective at weight loss than orlistat and showed that participants taking liraglutide were twice as likely to achieve more than 5% weight loss than orlistat.

Due to the relationship between obesity, blood sugar levels, and cardiovascular disease, research shows a positive relationship between GLP-1s and heart disease risk factors such as high blood pressure (hypertension) and triglyceride levels.

Interestingly, more recent studies have shown that semaglutide (Wegovy and Saxenda) is more effective at supporting weight loss and type 2 diabetes than liraglutide (Saxenda).

Even more recent trials suggest that tirzepatide (Mounjaro) is more effective than semaglutide and liraglutide (Wegovy and Saxenda) at supporting weight loss and type 2 diabetes.

Key points:

  • GLP-1 receptor agonists (GLP-1s) are a class of medications that mimic the actions of the hormone GLP-1, which helps regulate hunger and blood sugar levels
  • GLP-1s help the pancreas release more insulin, delay stomach emptying, and reduce appetite
  • GIP mimetics mimic the action of the hormone GIP, which improves insulin secretion to lower blood glucose and helps the body store fat in the adipose tissue, protecting the internal organs from excess energy storage
  • Two well-known GLP-1 medications in the UK and U.S. are liraglutide (Saxenda) and semaglutide (Wegovy and Saxenda)
  • Mounjaro is the only GLP-1+GIP mimetic medication currently available in the U.S., its release in the UK is not known
  • Research has suggested that GLP-1s are more effective at supporting weight loss than other weight loss medication drugs like Orlistat
  • A systematic review and meta-analysis found that all five weight loss medications investigated were more effective than placebo at supporting weight loss
  • Liraglutide was more effective at weight loss than orlistat. Semaglutide is more effective at supporting weight loss and type 2 diabetes than liraglutide; at the same time, tirzepatide is more effective than semaglutide and liraglutide.

2) Mounjaro and Saxenda for weight loss and type 2 diabetes

Type 2 diabetes

The hormone GLP-1 binds to GLP-1 receptors in the pancreas to increase insulin release after a meal. It also prevents the body from releasing too much glucagon, a hormone that increases blood sugar levels.

These two mechanisms support individuals living with type 2 diabetes in managing their blood glucose levels on a meal-to-meal basis.

Research has shown that GLP-1s are effective at reducing blood glucose for people living with type 2 diabetes.

Liraglutide (Saxenda) was one of the earlier forms of longer-lasting GLP-1s, while tirzepatide is a dual-action type 2 diabetes medication.

Alongside its effects on GLP-1, tirzepatide mimics the actions of another hormone called GIP (gastric inhibitory polypeptide) that reduces blood sugar levels.

Liraglutide reduces HbA1c (average blood glucose) levels by around 1.3% on average and fasting plasma glucose by 2 mmol/L.

In comparison, studies have shown that tirzepatide is more effective and reduces HbA1c levels by up to 2.3% and fasting plasma glucose by 3 mmol/L.

Liraglutide is available in the UK and the U.S. to treat type 2 diabetes. However, tirzepatide is only available in the U.S. after getting FDA approval in 2022; the UK will likely approve tirzepatide in the not-to-distant future.

So, GLP-1 receptor agonists significantly reduce blood sugar levels and are an effective treatment for type 2 diabetes—particularly the longer-lasting and recent versions of GLP-1s, semaglutide and tirzepatide.

Interestingly, the lasting effect of GLP-1s to support type 2 diabetes might be its impact on reducing appetite and supporting weight loss than the impact it has on the pancreas.

Weight loss

Compared to lifestyle interventions without medications, GLP-1-assisted programmes have been shown to lead to a more clinically significant weight loss of 10% or more.

Losing and maintaining weight loss of more than 10% is associated with significantly reducing complications associated with obesity, including hypertension, type 2 diabetes, and heart disease.

Studies have shown that liraglutide leads to an average weight loss of 6.4%. Comparatively, tirzepatide leads to a weight loss of up to 21%, depending on the dose.

5mg of tirzepatide leads to around 15% weight loss, 10mg 19%, and 15mg 21%.
So, GLP-1s lead to clinically significant weight loss rarely observed in intervention trials that use lifestyle interventions without medications.

Tirzepatide is the most effective GLP-1 medication and leads to more clinically significant weight loss than liraglutide.

Key points:

  • GLP-1 hormone increases insulin release after a meal and prevents the release of too much glucagon, helping manage blood glucose levels in individuals with type 2 diabetes
  • GLP-1 receptor agonists, particularly longer-lasting versions semaglutide and tirzepatide, are effective in reducing blood sugar levels
  • Tirzepatide is a dual-action medication that mimics the actions of GIP, reducing blood sugar levels further
  • GLP-1s also reduce appetite and support significant weight loss of more than 10%, which is associated with reduced complications of obesity
  • Tirzepatide is more effective than liraglutide in reducing both blood sugar levels and weight

Want to make losing weight feel easier?

Second Nature uses science to help you make healthy choices, ensuring they stick in the long run. Join the 150,000 people on a Second Nature journey today by taking our quiz. We use your quiz answers to tailor our advice and support on the programme, to ensure you lose weight and keep it off.

3) Mounjaro VS Saxenda: Which one should you choose?


Mounjaro is a more effective drug than Saxenda. As demonstrated above, tirzepatide (the active ingredient in Mounjaro) leads to more clinically significant weight loss and blood sugar reductions than liraglutide (the active ingredient in Saxenda).

So, if you were looking at trying GLP-1 medications for weight loss or blood sugar improvements, Mounjaro would be the better choice.

However, the drugs differ in their side effects and safety profiles which might influence your decision.

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 constipation, 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.

The main side effects of tirzepatide and liraglutide are GI-related, such as nausea, vomiting, constipation, and diarrhoea.

However, tirzepatide appears to be better tolerated than liraglutide. Studies have shown that between 5-10% of participants discontinue their tirzepatide medication due to side effects, compared with 27% on liraglutide.



Mounjaro isn’t currently available in the UK. In the US, the cost of Mounjaro on a monthly basis will depend on various factors, such as your prescription drug insurance plan, your pharmacy, and any available discounts or savings programmes.

However, the current retail cost for Mounjaro is around $1500 a month.


The cost depends on where you’re purchasing it from and how long you intend to use the medication. However, to purchase the medication and injectable pens required for 56 days would cost £323.99, or around £160 per month.

The price would then increase incrementally the longer you use the medication. Saxenda® is generally recommended for up to 12 weeks, costing anywhere between £485-£540.

Saxenda® is available on prescription in UK pharmacies if you’re eligible.

In the U.S., the cost depends on where you’re purchasing it from and how long you intend to use the medication.

However, the current price for a complete package of Saxenda® in the U.S. is around $1,430. Check with your insurance provider to see if they will cover all or some of this.

Key points:

  • Mounjaro® is more effective than Saxenda® at supporting weight loss and blood sugar reductions
  • However, Saxenda® 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
  • Saxenda® is currently available in the UK and the U.S.
  • Mounjaro® is only available in the U.S. at the moment, the UK is yet to confirm when the drug will be made available
  • Both medications are expensive if you opt to purchase them privately.
  • Currently, only Saxenda® is available to purchase in the UK outside of a prescription and would cost around £160 a month whilst you’re taking the medication.

Take home message

The recent innovations in GLP-1 medications are pretty remarkable and have caused quite a stir in the world of healthcare.

We’re in new territory where obesity and type 2 diabetes medications treat an underlying cause instead of merely treating the symptoms to support better management.

However, these drugs shouldn’t be seen as miracle cures; they’re not designed to be used for life.

They’ve been designed to be taken alongside lifestyle changes that will enable you to eventually come off the medications and maintain your lower weight for the long term.

The harsh reality is that we still don’t know the long-term effects of these medications on our health. There are examples of drugs being withdrawn from the market as more long-term data comes to light.

Lorcaserin was a weight loss drug approved by the Food and Drug Administration (FDA) in the U.S. but was recently withdrawn as data indicated that it increased cancer risk.

The example of lorcaserin is why you must weigh the pros and cons when your doctor prescribes medication or before you purchase it yourself and start treatment. Report any side effects to your healthcare team.

GLP-1s are safe and effective for most people in the short to medium term, but we don’t have long-term data to be sure they’re not causing severe adverse effects elsewhere.

At Second Nature, we’re not against using medications to support people in making healthy changes and reducing their risk of chronic disease.

However, we don’t recommend using medications as a reason not to make healthy lifestyle changes. The causes of obesity and type 2 diabetes aren’t merely rooted in biology but also psychology and sociology.

With these medications, you may lose weight and reduce blood sugar levels. But will you be happier? Will you be more fulfilled? Will you be content with your life and social relationships?

For that, you may need to consider a lifestyle change, and if that’s something you want to commit to alongside taking GLP-1 medications, Second Nature is launching a new GLP-1 assisted weight loss programme this spring.

But we have limited space available; register your interest here.

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