Arrone, Louis J, et al. “Continued Treatment with Tirzepatide for Maintenance of Weight Reduction in Adults with Obesity.” JAMA, vol. 331, no. 1, 2023, pp. 38-48. pmc.ncbi.nlm.nih.gov/articles/PMC10714284.
When it comes to weight loss medication, you've got two main options: weekly injections like Mounjaro and Wegovy, or daily pills like orlistat and the Wegovy pill. The Wegovy pill is the first oral GLP-1 approved for weight loss and is now available in the UK.
Weight loss injections currently come out on top for results: people taking Mounjaro can lose up to 22.5% of their starting weight, and people on the 7.2mg dose of Wegovy lost 20.7% in a clinical trial. Tablets like orlistat tend to produce more modest weight loss, though semaglutide in tablet form is changing the picture.
So, which should you go for: weight loss injections or pills? Because everyone's different, we can't say for sure how a particular medicine might affect you personally. But we can weigh up the pros and cons of each option, and dig into the scientific research to see which works best for whom.
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Which weight loss injections and pills are available in the UK?
Here are the most commonly-prescribed weight loss injections and pills in the UK. And FYI: all of them are meant to be taken alongside healthy lifestyle changes.
Weight loss injections
These work by making you feel full, so you eat less. We’ve explained how they do that in more detail further down the page.
Mounjaro
Using the active ingredient tirzepatide, Mounjaro works by behaving like two natural hormones: GLP-1 and GIP. This dual action is what makes it so potent.
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Wegovy
Wegovy only mimics the effects of GLP-1 (this type of medicine is called a GLP-1 receptor agonist). That means it brings on the effects of one hormone, rather than two like Mounjaro. Its active ingredient is semaglutide.
Saxenda
And then we have Saxenda, another GLP-1 receptor agonist. Though it uses a different active ingredient than Wegovy, liraglutide.
For a detailed comparison of Wegovy and Saxenda, see our guide.
(And if you’re curious about new injectables coming soon, you might want to read about Survodutide, a GLP-1/glucagon receptor agonist still in trials, as well as CagriSema, which combines semaglutide and cagrilintide for even greater appetite control.)
Weight Loss Pills
Wegovy pill
The Wegovy pill is the first oral GLP-1 medicine approved for weight loss. It contains semaglutide, the same active ingredient as the Wegovy injection, in tablet form. In clinical trials, it produced an average of 16.6% weight loss over 64 weeks, with around one in three people losing 20% or more. The Wegovy pill is now approved in the UK by the MHRA and available to order with Voy.
Rybelsus
Rybelsus is another semaglutide tablet, but it's licensed for type 2 diabetes in the UK rather than weight loss. It's a lower dose than the Wegovy pill. Some private clinics prescribe Rybelsus off-label for weight loss, though it produces less weight loss than the Wegovy pill in clinical trials.
Orforglipron (Foundayo)
Orforglipron, sold as Foundayo, is another oral GLP-1 medicine for weight loss and type 2 diabetes. It's now approved in both the US and UK, and can be taken at any time of day, with or without food. In clinical trials, people on the highest dose lost up to 12.4% of their body weight over 72 weeks.
Orlistat
Orlistat is the only weight loss pill you can get on the NHS, and one of the weight loss pills we offer at Voy, alongside the Wegovy pill. Unlike the Wegovy pill and Rybelsus, orlistat doesn't suppress appetite. Instead, it reduces the amount of fat you absorb from your food.
How do weight loss injections work?
We’re glad you asked. Weight loss injections make you feel full by acting like hormones that are released when you eat: either just GLP-1 (Wegovy and Saxenda) or GLP-1 and GIP (Mounjaro). That means they bring on the same effects that those hormones naturally would in the body.
To be more specific they stimulate the production of insulin after you eat (which tells the brain you’re full), tell the brain to lower your appetite, and slow the rate of digestion (this makes you feel fuller for longer).
Mounjaro does the above via the effects of two hormones rather than one.
Orlistat takes another approach entirely—it prevents your gut from absorbing fat from your diet. This fat then comes out in your stools.
Pros and cons of weight loss injections vs pills
Okay, now let’s get into the nitty gritty: how do weight loss pills stack up against injections?
Effectiveness
Injections still come out on top for results, but the gap is narrowing as semaglutide is now available in tablet form. On average, studies have shown that:
- People taking Mounjaro lost around 22.5% body weight after 88 weeks.
- People taking Wegovy lost around 15% body weight on average after 68 weeks. New research looking at people taking a higher dose, 7.2mg, shows a mean weight loss of 20.7% after 72 weeks.
- People taking the Wegovy pill at 25mg daily lost up to 16.6% body weight over 64 weeks.
- People taking orforglipron (Foundayo) at the highest 17.2mg dose lost up to 12.4% body weight over 72 weeks.
- After a year on Saxenda, people lost 7.4% body weight on average.
Roughly one in five people on orlistat lost at least 10% body weight after a year.
Ease of use
Pills are easier for anyone who prefers not to inject themselves or has a needle phobia. Injector pens are pretty simple to use, and for most people, the pain is either very mild or non-existent, but the appeal of a daily tablet over a weekly jab is real.
Dosing differs between treatments. Weight loss injections are mostly taken weekly, although Saxenda is taken every day. The Wegovy pill and Rybelsus are taken once daily on an empty stomach, with a 30-minute wait before eating or drinking anything other than water. Orlistat is taken up to three times a day, but only with meals that contain fat.
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Side effects
Side effects are common for any of the medicines we’ve mentioned and can affect over one in ten people. Mostly though, they’re manageable and clear up on their own.
Symptoms from GLP-1 medications (including injections like Mounjaro and Wegovy, and tablets like the Wegovy pill) tend to affect the gut: think nausea, vomiting, diarrhoea, and constipation. If you're taking Mounjaro, here's a breakdown of its side effects.
With orlistat, the most common symptoms include headache, abdominal pain, and passing oily stools more frequently.
Heads up: this isn’t a full list of all possible side effects. And if your symptoms get worse, are bothering you, or don’t go away, speak with your prescriber.
Side effects support at Voy
"If you're using Voy and you experience any side effects, rest assured that our expert clinicians are just a message or phone call away. They can adjust your dose, prescribe medication to ease your symptoms, or simply offer reassurance.
Everyone responds differently to weight loss treatment and we'll help you find what feels right for you."
Cost
Cost varies depending on which pill or injection you choose. Orlistat is the cheapest option and is generally cheaper than weight loss injections in the UK. The Wegovy pill is now available in the UK, starting from £69 a month for the lowest dose on a 6-month plan with Voy, which is in a similar range to current Wegovy injection pricing.
Choosing the right weight loss medication for you
The best weight loss medication for you depends on your starting weight, health history, lifestyle, how well you tolerate treatment, and whether you prefer a tablet or injection. Here's a quick guide:
- For the strongest weight loss results: Mounjaro (up to 22.5%) or Wegovy (up to 20.7% at the 7.2mg dose)
- For an oral GLP-1 option: The Wegovy pill or orforglipron (Foundayo), both now approved in the UK.
- For people with PCOS or insulin resistance: GLP-1 medications that also improve insulin sensitivity
- For a non-GLP-1 option: Orlistat tablets, available on the NHS or privately
Whatever you choose, weight loss medication works best alongside a balanced diet and regular exercise. It's not a quick fix. To see the full benefits, you usually need to take it for at least a year, and your prescriber will recommend the right option for your situation.
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Your weight loss journey
You're not on this journey alone. At Voy, you'll get weight loss medication (Mounjaro, Wegovy, the Wegovy pill, or Orlos) alongside one-to-one access to our clinicians, who'll create a treatment plan that works for you.
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DisclaimerAt Voy, we ensure that everything you read in our blog is medically reviewed and approved. However, the information provided is not meant to replace professional medical advice, diagnosis, or treatment. It should not be relied upon for specific medical advice.
References
¹²“Dietary Advice for Patients Taking Orlistat: Patient Information.” University Hospitals Coventry and Warwickshire NHS Trust. (2022). Accessed 8 Jan. 2025. www.uhcw.nhs.uk/download/clientfiles/files/Patient%20Information%20Leaflets/Clinical%20Support%20Services/Dietetics/Dietary%20advice%20for%20patients%20taking%20orlistat.pdf.
³Eli Lilly and Company. "FDA Approves Lilly's Foundayo™ (Orforglipron)..." Eli Lilly and Company Investor Relations, 1 Apr. 2026, investor.lilly.com/news-releases/news-release-details/fda-approves-lillys-foundayotm-orforglipron-only-glp-1-pill.
