Wegovy (Ozempic): how does it work?

The science behind weight loss: how Mounjaro and Wegovy work

In this guide

Wegovy (Ozempic): how it works

Wegovy and Ozempic explained

Wegovy and Ozempic are injectable medications with the active ingredient semaglutide. Both are available on prescription in the UK.

Wegovy is prescribed to patients with obesity to help them lose weight. Ozempic is used to treat type 2 diabetes.

In this guide, we explain semaglutide's mechanism of action for weight loss. We also explore another weight loss medication called 'Mounjaro' and explain how it works.

How hunger works in the body

Before we look at Wegovy and how it works, let's take a moment to understand the science behind hunger.

It's tempting to think of our bodies as being like cities. The brain is one building and the gut is another. They each have a job to do and they're quite happy to get their work done without interference from the other.

In reality, though, the body is more like a telephone exchange. Our brain is the communication centre – and it's linked to its fellow organs through a complex web of nerves and other systems. These organs are constantly sending messages to the brain and receiving instructions in return.

But how does the brain send these instructions? And how does the body know what to do with them?

That's where hormones come in. Hormones are one of the brain's main communication tools. They're chemicals that interact with parts of the body and tell those parts to act in a certain way.

There are many different types of hormones. Some of them are involved in hunger and satiety (feeling full). These 'hunger hormones' send messages to the body that tell us to eat or stop eating. One of the main types is a group called 'incretins'.

Incretins are released after we eat. They have a number of effects, including raising insulin levels and slowing down digestion. Together, these effects help us feel full and reduce food cravings.

The Wegovy (Ozempic) mechanism of action

Now we know that hormones help control hunger – and one of the main types of hormones involved is incretins.

Wegovy's active ingredient, semaglutide, is an incretin mimetic. Or, to put it another way, it's a very good actor. Semaglutide mimics one of the main incretin hormones (GLP-1) and has similar effects on the body.

When you take Wegovy, you play a trick on your own digestive system. As far as your body is concerned, it's getting more of the GLP-1 hormone and it will respond in the same way.

That's why Wegovy can help with weight loss. Like GLP-1, it slows down digestion, regulates blood sugar levels and helps control food cravings. The difference is that you don't have to eat to get these effects – Wegovy can make you feel full even when you haven't eaten.

Mounjaro: how does it work?

Like Wegovy, Mounjaro is an injectable weight loss medication available on prescription in the UK.

Mounjaro is a newer drug with a different active ingredient. While Wegovy contains semaglutide, Mounjaro's mechanism of action for weight loss relies on an ingredient called 'tirzepatide'.

Tirzepatide and semaglutide work in a similar way. They both mimic our bodies' natural incretin hormones to help us feel full and control food cravings.

However, there's a big difference between the two. Semaglutide only mimics the GLP-1 hormone. Tirzepatide mimics GLP-1 and another incretin hormone called 'GIP'.

Do double hormones mean doubly good results? Not quite. However, Mounjaro is more effective on average than Wegovy. Patients who take Mounjaro tend to lose around 21% of their body weight with sustained treatment.¹ With Wegovy, the average weight loss is 15%.²

How do I know if I'm eligible for Wegovy or Mounjaro?

Remember that different medications work for different people. It's important to understand the possible side effects of each drug and seek medical advice before going ahead with any treatment.

SemaPen's weight loss programmes are designed by doctors in the UK. Our online consultation process makes it really simple to check whether you're eligible for Wegovy or Mounjaro. You can get started here.

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