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Zepbound and Wegovy are weight-loss injections for adults living with obesity alongside diet and lifestyle changes.
Wegovy is manufactured by Novo Nordisk, while Zepbound is by Eli Lilly. The active ingredient in Zepbound is tirzepatide, and semaglutide in Wegovy.
Based on data from randomised controlled trials, Zepbound appears to lead to more weight loss than Wegovy.
Research shows Zepbound supports average weight loss of around 25% after one year and 16% on Wegovy.
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 Zepbound and Wegovy?
Zepbound and Wegovy are GLP-1 receptor agonists, weight-loss injections that reduce appetite to support weight loss and improve blood glucose control through various mechanisms.
GLP-1 is a hormone that lowers hunger and food-seeking behaviours by communicating with the brain’s appetite control centre, the hypothalamus. Zepbound and Wegovy mimic the actions of GLP-1.
Zepbound, a GLP-1 receptor agonist, is also a mimetic of a hormone called glucose-dependent insulinotropic polypeptide (GIP).
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, Wegovy is a single-action medication that mimics one hormone in the body, while Zepbound has a dual function mimicking two hormones in the body that support blood glucose levels and weight loss.
Both medications have similar dosing schedules and are administered once a week. The main difference is the amount of medication used. The volume of the doses with Zepbound is larger than with Wegovy.
Zepbound and Wegovy dosing schedules:
Weight-loss injections aren’t 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 healthy journey while you commit to living a healthier lifestyle.
Weight-loss injections can help calm the ‘food noise’ and help you find your eating off-switch while developing the healthy habits needed to keep the weight off for good.
At Second Nature, we’ve been used by the NHS since 2017 to support people with type 2 diabetes and obesity to lose weight, manage their blood sugar levels and lead healthier lifestyles for the long term.
If you’re considering purchasing Zepbound or Wegovy 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 British Medical Journal 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 has launched a medication-supported programme combining a weekly weight-loss injection, like Wegovy or Zepbound, with our NHS-trusted weight-loss programme.
1) How do Zepbound and Wegovy 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 GLP-1 hormone produced by 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 Zepbound works
Zepbound is also known as a GLP-1 receptor agonist as it mimics the actions of the hormone GLP-1.
The active ingredient in Zepbound 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, Zepbound is known as a dual-action GLP-1 and GIP receptor agonist.
Like Wegovy, Zepbound 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
- Zepbound is a dual-action weight-loss injection and mimics the actions of the hormones GLP-1 and GIP
- Zepbound’s active ingredient is tirzepatide, and it’s manufactured by Eli Lilly
2) Do you lose more weight on Zepbound or Wegovy?
Data from randomised controlled trials suggests that Zepbound leads to more average weight loss than Wegovy.
One study found that Zepbound 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 Zepbound.
Additionally, research suggests the percentage of participants on Zepbound achieving more than 10% weight loss is considerably higher than Wegovy.
Achieving over 10% weight loss is associated with clinically significant reductions in risk of chronic conditions such as type 2 diabetes and heart disease.
A randomised controlled trial in 670 people showed that 92% of participants on Zepbound achieved more than 10% weight loss, with 84% achieving more than 15%.
In comparison, a randomised controlled trial in 1,961 people showed that 69% of participants on Wegovy achieved more than 10% weight loss, with 50% achieving more than 15%.
So, research suggests that Zepbound 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 Zepbound supports more average weight loss after one year
- Average weight loss on Zepbound after one year is around 25% and 16% on Wegovy
- Research shows more participants achieve more than 10% weight loss on Zepbound (~90%) than Wegovy (69%)
3) Zepbound vs Wegovy: Which one should you choose?
Effectiveness
Zepbound is potentially more effective for average weight loss than Wegovy based on data from randomised controlled trials.
As demonstrated above, tirzepatide (the active ingredient in Zepbound) appears to lead to greater weight loss than semaglutide (Wegovy) by around 9%.
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 be more effective.
Individual medication responses differ greatly, so it’s worth speaking with your healthcare provider to determine what would be best for you.
So, if you were looking at trying a weight-loss injection, Zepbound might be more effective on average, but both medications
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.
Ttirzepatide seems more effective at weight loss than semaglutide but may have a slightly 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
Zepbound cost
The cost depends on where you’re purchasing it from and how long you intend to use the medication.
However, to purchase Zepbound (Mounjaro) and the injectable pens required for four weeks would cost around £300 with Second Nature when it’s available.
We expect to launch our Mounjaro-supported weight-loss programme in February 2024.
In the U.S., the cost will depend on your insurance coverage, any discounts available, and your pharmacy. Typically, it will start at a lower cost of around $25 a month and rise after six months to anywhere between $1000-$1500.
Wegovy cost
The cost depends on where you’re purchasing it from and how long you intend to use the medication.
However, purchasing Wegovy and the injectable pens required for four weeks will cost £299 with Second Nature. This includes 1-1 access to a personal nutritionist and access to our award-winning app.
In the U.S., the cost will depend on your insurance coverage, any discounts available, and your pharmacy. Typically, it will start at a lower cost of around $25 a month and rise after 6 months to around $1500.
Key points:
- Zepbound is more effective than Wegovy at supporting weight loss and blood sugar reductions
- However, Wegovy may lead to fewer side effects and is better tolerated than Zepbound
- However, individuals will vary in their medication response, so choose the right one for you
- Both medications are expensive if purchased privately
Take home message
