How to compare weight loss programmes: pros and cons to look for
Comparing weight loss programmes is easier if you know what to look for. See 6 factors worth weighing up.

Weight loss programmes using injectable GLP-1 medications are becoming more widely known among the UK public – and ever more popular.
The best-known and most effective drugs within this category are Mounjaro and Wegovy (also known as Ozempic when prescribed for type 2 diabetes). Neither medication is widely available on the NHS. However, a raft of private clinics and online pharmacies have sprung up to meet demand.
For the thousands of people living with obesity who could benefit from these treatments, this is undoubtedly a good thing. But as options increase, so does the risk of analysis paralysis – or, in other words, having so many choices it's hard to know where to start.
That's where this guide can help. We show you what to look for in a weight loss programme and how to compare your options to find the best one for you.
Why compare weight loss programmes?
In some ways, deciding to compare weight loss plans is like choosing to shop around for car insurance or broadband providers.
You, the customer, are in control. While many online pharmacies will tell you they're the only option worth considering, it's ultimately about choosing the best programme for your needs.
In other ways, it couldn't be more different. When it comes to your weight and your health, the stakes are much, much higher than with broadband or flights or AI-powered home assistants. It's really important to make the right choice – and, ideally, get it right first time.
Unfortunately, there's not a lot of advice out there to help you choose. While we're not completely unbiased (SemaPen provides various medical treatments for obesity), we hope this guide helps you make an informed decision.
What NOT to compare
Weight loss medication suppliers can differ in many fundamental ways. However, the medication itself should be the same, no matter where you get it from.
In other words, Wegovy is Wegovy and Mounjaro is Mounjaro. You won't get a 'different Wegovy' or 'different Mounjaro' depending on the supplier you choose.
(That's assuming you get genuine, branded medication from a trustworthy and licensed supplier. Compounded and counterfeit weight loss injections are a whole different ball game.)
This means you can expect to:
- Lose an average of 21% of your starting weight with a full course of Mounjaro treatment
- Lose an average of 15% of your starting weight with a full course of Wegovy treatment
It's also not worth comparing side effects between suppliers. Remember: all legitimate Wegovy suppliers should supply the same Wegovy – and Mounjaro suppliers should supply the same Mounjaro. This means side effects won't differ depending on where you buy the drugs.
The most common side effects include mild nausea, vomiting, stomach aches and diarrhoea. Mounjaro can also cause hair loss or thinning (usually temporarily) and make the contraceptive pill work less effectively. You can learn more in our guide to the side effects of weight loss drugs.
What differs between suppliers?
So, legitimate suppliers will send chemically identical versions of each drug. As far as the medications go, it doesn't matter where you get them from.
However, each suppliers' weight loss programme works slightly differently.
Each offers different levels of support from different kinds of professionals. And they might differ on key details like the price of the medication and how you pay for it.
With that in mind, let's look at six factors worth considering when making your decision.
Factors to consider when comparing GLP-1 weight loss programmes
1. Expertise
Any good weight loss clinic should be licensed to provide prescriptions – that's non-negotiable. If there's no evidence of this – or if the provider offers weight loss drugs without a medical consultation – then click away and don't click back.

Even when you're sure the provider is legitimate, it's still worth poring over their qualifications. Many providers are pharmacies, first and foremost. They're not weight loss experts – they're pharmacists who happen to dispense weight loss medications.
This doesn't mean you're more at risk if you choose one of these pharmacies. However, it might backfire if you need to ask questions. Weight loss experts can provide tailored, considered advice, while non-experts are more likely to rely on canned responses.
And what if it turns out Wegovy or Mounjaro aren't the best treatments for you? Pharmacies can only dispense medications, so they're limited in the alternatives they can provide.
A real weight loss clinic, on the other hand, can offer a swathe of treatments, ranging from diet advice right up to bariatric surgery.
2. Experience
Imagine you're buying a boat. As you hand over the cash, the boatmaker tells you it's the first boat they've ever built. It might be a perfectly good boat – but chances are, you're now feeling a little less confident about that sea voyage.
It's the same with weight loss programmes. More experience on the provider's side means more peace of mind for you. It's that simple.
So, when comparing weight loss providers, take some time to learn about them and their stories. Were they born yesterday or do they have years of experience on their side?
You could start by looking at their 'About us' pages. If they've been operating for decades, they'll no doubt want to tell you about it. But if details are scant, that might be a sign they're a little wet behind the ears.
3. Support
Wegovy and Mounjaro aren't magic wands for weight loss. To get the results you want, you must follow a healthy, balanced diet and exercise regularly.¹ ² It takes willpower and effort to get it right.
That's why good support is crucial. Will your pharmacy or clinic simply sell you the medication and leave you to get on with it? If so, your weight loss journey might feel less like a guided tour and more like a solo mission to Mars.
Our advice: take a good look at each provider's support package. Does it feel right for you?
If you have bags of willpower and enjoy figuring things out on your own, you might be OK with a provider that offers limited support. But if you think you'll need an extra boost for those bumps in the road, look for one that offers tailored, ongoing advice at every step.
4. Safeguards and guarantees
If you're new to weight loss medications, it's understandable that you might feel a teensy bit sceptical. Sure, you've seen what the results are like for most people – but what if it doesn't work for you?
It's true that a small amount of people don't get the results they want from weight loss injections, even if they follow all the guidelines. That's why it's worth looking for providers that offer some sort of guarantee or safeguard in case the weight you lose doesn't meet expectations.

This one's more of a perk than an essential. However, it does mean extra reassurance that your provider is on your side and set up for your success.
5. Subscriptions
Broadly speaking, there are two forms of medical weight loss programmes:
- Transactional, where you pay for each dose of the medication as and when you need it.
- Subscription, where the provider automatically sends the dose you need on a rolling schedule.
It's up to you to decide which best suits your needs. With a transactional model, you might have more freedom to switch providers and manage your medication as you see fit. However, signing up for a subscription means you'll never forget to order a new dose or which dose you need. Subscription-based providers also tend to offer more perks, such as tailored advice and weight tracking.
6. Price
Price is obviously an important consideration – indeed, for people with tight budgets, it might be the most important.
However, it's worth remembering that you get what you pay for. If you only want the medication, you might be able to get away with choosing the cheapest provider you can find. But if you want ongoing advice and other benefits, you may have to pay a little bit more.
How SemaPen compares to other providers
Look. We're not going to tell you that SemaPen is the only option worth considering for injectable weight loss medication. At the end of the day, the decision is up to you.
That said, we firmly believe that our weight loss programmes offer something truly unique: years and years of real obesity expertise.
SemaPen is part of Phoenix Health – the only bariatric clinic trusted by the NHS to provide treatment. And we were founded by Professor David Kerrigan – a leading UK obesity expert and the former president of the British Obesity & Metabolic Surgery Society.
Best of all, this expertise is available to you throughout your weight loss journey. As you progress with Wegovy or Mounjaro, we'll monitor your success using smart digital scales and offer helpful tips to help you stay on track.
And that's not all. Here's a quick comparison of our weight loss programmes compared to a leading competitor (not naming names):
SemaPen | Leading competitor | |
---|---|---|
Type of business | Obesity clinic founded by leading UK specialists | An online pharmacy |
Support staff | Weight management experts, including doctors, psychologists, dieticians and specialised nurses | Pharmacists and GPs |
Years of experience | More than 20 years | Around 3 years |
Treatments available | Mounjaro and Wegovy injections, plus dietary advice, psychological support and bariatric surgery | Injections only |
Advice offered | Proactive advice offered throughout treatment | Support offered only at initial consultation |
Direct support available | Yes – to real obesity experts | Yes – to pharmacists and support staff |
Digital weight-tracking scale | Yes | No |
Weight loss app | Yes | No |
Weight loss rewards | Yes | No |
Money back guarantee | Yes* | No |
Cancel anytime | Yes** | No subscription available |
Are you interested in trying SemaPen's expert-led, at-home weight loss programmes? You can take our simple online consultation to find out if you're eligible. Developed by leading UK obesity experts, it tells you instantly whether Mounjaro or Wegovy is right for you.
Sources and small print
1. Jastreboff, A.M. et al. (2022) "Tirzepatide Once Weekly for the Treatment of Obesity" The New England Journal of Medicine, 387(3) https://doi.org/10.1056/NEJMoa2206038
2. Wilding, J.P.H. et al. (2021) "Once-weekly semaglutide in adults with overweight or obesity" The New England Journal of Medicine, 384(11) https://doi.org/10.1056/NEJMoa2032183
* Terms and conditions apply.
** An admin fee may apply for early cancellation. Please see our terms and conditions for more information.
This article was reviewed and approved by Alice Fletcher, Lead Bariatric Dietician, and Lujain Alhassan, Bariatric Nutritionist, on 20 May 2025.