GLP-1 stands for glucagon-like peptide-1. Your gut releases it every time you eat. It tells your pancreas to put out insulin, tells your liver to hold back glucagon, slows down how fast your stomach empties, and reaches the part of your brain that decides you have had enough.
In plainer words: GLP-1 is the signal that tells your body food has arrived. It helps your body deal with the sugar in that food. It slows your stomach, so what you have eaten sits there longer and you feel full for longer. And it reaches the part of your brain that decides you have had enough, which is why it changes how hungry you feel rather than how much willpower you have.
So GLP-1 is not a drug and it is not a brand. It is a hormone you make already. What people mean when they say they are “on GLP-1” is a medicine that copies it and lasts far longer than the real thing does.
What the medicines actually do
Semaglutide acts on the GLP-1 receptor and nothing else. Tirzepatide acts on that receptor and on the receptor for GIP, a second gut hormone, and it binds more tightly to the GIP one. That is the whole difference between the two molecules everybody is talking about.
Neither of them burns fat. They work on appetite and on the way your body handles glucose. If somebody describes one of these as a fat burner, they have not understood it.
The names you may have heard
All of these are one of those two molecules under a trade name. What each one is licensed to be sold for is not the same everywhere, and it is worth knowing that some of them are licensed for diabetes rather than for weight.
- Ozempic Semaglutide, injected once a week, sold for type 2 diabetes.
- Rybelsus Semaglutide as a tablet, sold for type 2 diabetes.
- Wegovy Semaglutide, injected once a week, sold for weight management and to reduce cardiovascular risk.
- Mounjaro Tirzepatide, sold for type 2 diabetes.
- Zepbound Tirzepatide, sold for weight management and for obstructive sleep apnoea.
What it feels like
Most of what people notice is their stomach, and most of it is mild to moderate. Nausea is the common one. Vomiting, diarrhoea, stomach pain, constipation, indigestion and belching all happen too, and they happen because the medicine is slowing your stomach down, which is part of how it works rather than a sign something has gone wrong.
It depends on the dose, and it is at its worst in the weeks just after a dose goes up. For most people it settles as the body gets used to that dose.
Which is the reason the dose is not where it ends up on day one. You start low, and it goes up in steps with weeks in between. How fast is your doctor’s decision and she makes it with you: if a step is hard on you, you stay on it longer, or you go back down a step before trying again. There is nothing to be won by getting to a higher dose sooner, and going up faster than you are comfortable with is how people end up feeling ill enough to stop altogether.
The less common ones, so that you have heard of them rather than to alarm you. Gallstones. Existing diabetic eye disease getting worse for a while when blood sugar falls quickly. A small rise in resting heart rate. For tirzepatide, the British medicines regulator warned in 2026 about a small risk of severe inflammation of the pancreas. Your doctor goes through these with you, and she is the person to tell if something does not feel right.
Fat is not the only thing you lose
When weight comes off, some of what goes is muscle. That is true of any way of losing weight, not just this one, and it is truer the faster the weight comes off. It matters more than it sounds, because muscle is a large part of what your body burns at rest. Lose enough of it and you end up lighter with a slower metabolism, which is the worst of both and is a large part of why weight so often comes back.
Two things protect against it, and neither is optional. Enough protein, every day, which is harder on a medicine that takes your appetite away and is the single most common thing to get wrong. And resistance training, meaning lifting something heavy enough to be hard, two or three times a week. Walking is good for you and it is not this.
This is why the programme is not only a prescription. What you eat and how you train are the part you keep.
Who these are not for
Anyone with a personal or family history of medullary thyroid cancer should not take them, and neither should anyone with multiple endocrine neoplasia type 2. That is not a formality and it is why our intake asks you about it before anything else happens.
There are other reasons a doctor would say no, including where you are in your life with pregnancy. Your doctor goes through the rest with you on your consult. the rest pending our clinician
What happens if you stop
When people stop taking these medicines, the weight tends to come back.
So it is not a course you finish. Anybody selling you a box and wishing you luck has left out the part that decides whether this works. It is also the reason our follow-up visits are booked for you rather than left to you to remember.
That is not the whole story, though. How much comes back depends a great deal on what you were given alongside the medicine. It takes your appetite down; it does not build you any muscle, teach you to cook, or change what you reach for when you are tired. Those are the things that hold weight where it is, and they are the reason this programme is built around food and training from the first week rather than the last.
So the honest way to think about it is that the medicine is doing most of the work at the start, and the work moves across to you as you go. How far it moves, and whether you and your doctor decide at some point that you do not need the medicine any more, depends on what you have built by then and on your own body. That is a conversation to have with her rather than a promise this page can make you. What is certain is that the muscle you keep and the way of eating you learn stay yours whatever happens to the prescription.
What we do, and what we do not
Every member has a video consult with a doctor before anything is prescribed. There is no faster route and no tier that buys one. Your doctor is looking for the reasons this medicine would be wrong for you, and if she finds one she will say so and tell you why. A nutrition-led plan instead is a real answer, not a consolation prize.
We do not sell medicine from this page. There is nothing on it to buy and no way to buy it.