Which GLP-1 is best for weight loss?

SURMOUNT-5: tirzepatide versus semaglutide, directly

This trial randomised adults with obesity to tirzepatide or semaglutide and ran them side by side for 72 weeks. Tirzepatide produced substantially greater average weight loss, roughly 20% against roughly 14%. Because both arms ran under identical conditions, this is far stronger evidence than comparing SURMOUNT-1 with STEP 1 and hoping the populations matched.

The critical caveat, and most articles still miss it: SURMOUNT-5 compared tirzepatide against semaglutide at 2.4mg, which was the maximum licensed dose at the time. The UK now licenses semaglutide at 7.2mg, which reached around 20.7% in its own trial. No head-to-head trial has yet compared tirzepatide against semaglutide 7.2mg, so anyone claiming a definitive winner at the top of the dose range is going beyond the evidence.

What none of it tells you: which one you will tolerate, which one you can afford, or which one your prescriber considers appropriate for your history. It is one input, not a verdict.

• What the trial showed: in STEP UP, 7.2mg produced around 20.7% average weight loss against about 17.5% for 2.4mg over 72 weeks, with roughly a third of participants losing 25% or more of their body weight, a threshold previously associated with surgery
• Tolerability: broadly comparable to 2.4mg in the trial, though side effects remain dose related and titration is still gradual
• Who it is licensed for: adults with a BMI of 30 or above. It is not licensed below that threshold, and not for people using semaglutide specifically to reduce cardiovascular risk
• Not a starting dose: you cannot begin here, and you cannot switch across from Mounjaro straight onto it. Everyone titrates up from 0.25mg
• NHS status: private only for now. NICE appraisal is the route to NHS funding and has not concluded

Wegovy pill (oral semaglutide 25mg), licensed 11 June 2026

• Effectiveness: around 13.6% average weight loss over 64 weeks in OASIS 4, rising to roughly 16.6% among people who took it exactly as directed
• The catch, and it is a real one: it must be swallowed whole on an empty stomach after at least 8 hours without food, with a sip of plain water, then nothing to eat or drink for 30 minutes. Absorption collapses if that routine slips
• Dosing: 1.5mg, then 4mg, 9mg and 25mg, at least a month at each step
• Switching: the MHRA has confirmed people already on the 2.4mg weekly injection privately can move straight to the 25mg daily tablet without retitrating

Foundayo (orforglipron), licensed 10 August 2026

• Effectiveness: around 11.2% average weight loss over 72 weeks at the highest dose, the lowest of the modern options
• The advantage: no fasting window, no water restriction, no fixed time of day. It is a non-peptide small molecule, so it does not need the absorption tricks oral semaglutide relies on
• Also licensed for type 2 diabetes, and the UK was the first country in Europe to authorise it
• Availability: private prescription availability begins 24 August 2026. NICE guidance on NHS use is due in November 2026, so there is no NHS route yet

• GLP-1 patches: these peptides are not absorbed through intact skin in any meaningful quantity. A patch cannot deliver a GLP-1 medicine
• GLP-1 drops and sprays: sold as “GLP-1 boosters” or “activators”. They do not contain licensed GLP-1 medicines
• GLP-1 supplements and gummies: typically fibre, berberine or similar ingredients marketed to borrow the language of prescription medicines
• Injections sold without a prescription: the genuinely dangerous category. Unlicensed and counterfeit pens circulate, dosing errors have caused serious harm, and you have no idea what is in the vial. The MHRA has repeatedly warned about this

• Prices vary substantially between GPhC-registered pharmacies for exactly the same medicine and dose
• The cheapest pharmacy at your starting dose is often not the cheapest at your maintenance dose
• First-order discounts can mask higher ongoing prices, so compare the repeat price
• Check delivery charges and whether prices include the consultation

• A BMI of 30 or above, or
• A BMI of 27 or above alongside a weight-related condition such as type 2 diabetes, high blood pressure, high cholesterol or obstructive sleep apnoea
• Lower BMI thresholds may apply for some ethnic groups, where risk occurs at lower body weight

• Can you commit to injections? If needles are a genuine barrier, the daily tablet may beat a “better” injection you never start
• What can you afford monthly for a year? Not the first month; the twelfth
• What else is going on medically? Established cardiovascular disease, diabetes, kidney or gastrointestinal conditions can all shift the answer
• How much weight do you need to lose? Someone targeting 5% and someone targeting 25% may reasonably choose differently
• What does your prescriber say? They see your full history, and they are the only person who can lawfully make this decision with you

Which GLP-1 is most effective for weight loss?

Tirzepatide (Mounjaro) at around 20 to 21% and semaglutide at the 7.2mg dose (Wegovy) at around 20.7% now sit close together at the top. Tirzepatide beat semaglutide in the SURMOUNT-5 head-to-head, but that trial used the older 2.4mg dose, and no trial has yet compared it against 7.2mg. Effectiveness for you personally depends on dose reached, tolerability, how long you continue and the lifestyle changes alongside it.

Is Mounjaro better than Wegovy?

For average weight loss, the evidence favours Mounjaro, including in the one trial that compared them directly. Wegovy holds a licensed indication for reducing cardiovascular events in eligible people with established cardiovascular disease, which can make it the better clinical choice for some. Better depends on which outcome matters most for you.

Which GLP-1 is best over the counter?

None. Every genuine GLP-1 medicine in the UK is prescription-only. GLP-1 patches, drops, gummies and supplements are not GLP-1 medicines, and injections sold without a prescription may be counterfeit or unlicensed and are genuinely dangerous. The only over-the-counter weight loss medicine in the UK is low-dose orlistat (Alli), which is not a GLP-1.

Is there a GLP-1 tablet for weight loss in the UK?

Yes, two. The Wegovy pill (oral semaglutide 25mg) was licensed on 11 June 2026 and averaged around 13.6% weight loss in OASIS 4, but must be taken fasted with strict timing. Foundayo (orforglipron) followed on 10 August 2026, averaging around 11.2%, and can be taken at any time with no food or water rules. Rybelsus is lower-dose oral semaglutide licensed for type 2 diabetes, not weight management.

Is Wegovy 7.2mg better than Mounjaro?

Their trial averages are close, roughly 20.7% for semaglutide 7.2mg in STEP UP and roughly 20 to 21% for tirzepatide in SURMOUNT-1, but they have never been compared directly at these doses, so neither can be called the winner on current evidence. Wegovy 7.2mg is licensed only for a BMI of 30 or above and not for cardiovascular risk reduction, so eligibility may decide it before effectiveness does.

Which GLP-1 tablet is best, the Wegovy pill or Foundayo?

The Wegovy pill shows higher average weight loss, but it demands an 8-hour fast, a sip of water only, and a further 30 minutes without food or drink every day. Foundayo averages less but has no food, water or timing restrictions. The better tablet is the one you can realistically take correctly for a year or more.

How much weight can I expect to lose?

Trial averages are roughly 20% with tirzepatide, 15% with semaglutide, 11 to 12% with orforglipron and 8% with liraglutide, but individual results vary widely around those averages. Weight loss depends on the dose reached, how long you continue, and the diet and activity changes alongside treatment.

Do I need a prescription?

Yes. All GLP-1 medicines for weight management are prescription-only in the UK, and a qualified prescriber must assess your eligibility and medical history before treatment starts. Pharmacies supplying them must be GPhC-registered.