The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
What is Tizepatide? UK Health Guide
Tizepatide is a prescription-only weight management injection licensed in the UK under the brand name Mounjaro. It's a dual GIP and GLP-1 receptor agonist, which means it works differently from other weight loss medications by activating two natural hormone pathways. If you're exploring weight management options as part of your UK health journey, understanding how tizepatide works, who can access it, and what to expect is important for making informed decisions with your GP or a licensed prescriber.
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Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
How Tizepatide Works and What It Does
Tizepatide activates two hormone pathways — GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) — which is what makes it unique in the UK weight management landscape. Unlike single-action GLP-1 medications, this dual mechanism may help regulate appetite more effectively, reduce food cravings, and support feelings of fullness after smaller meals.
The medication also slows gastric emptying (how quickly food leaves the stomach), though this effect typically reduces over time. Clinical trials showed that tizepatide helped participants lose an average of 15–21% of their body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity. Individual results vary significantly — weight loss depends on your starting weight, lifestyle changes, dose, and individual metabolism. Try our free GLP-1 weight loss calculator to estimate potential outcomes at different doses.
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Eligibility, Doses, and UK Access
In the UK, tizepatide is prescribed for adults with a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Lower BMI thresholds may apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage due to higher health risks at lower weights.
Tizepatide is available in doses from 2.5 mg to 15 mg, taken once weekly. Access in the UK is through NHS specialist weight management services (though waiting lists vary by region) or private prescribing following a clinical assessment. A prescriber will evaluate whether tizepatide is suitable based on your individual health, medications, and circumstances. Use our BMI calculator to check where you stand, and discuss options with your GP.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Is tizepatide the same as Mounjaro?
Yes. Tizepatide is the active ingredient in Mounjaro, the brand name used in the UK. Mounjaro is a prescription-only weight management injection containing tizepatide, licensed by the MHRA for adults with obesity or overweight with health conditions.
How quickly does tizepatide cause weight loss?
Weight loss typically begins within the first few weeks but is gradual and sustainable. Clinical trials showed average weight loss of 15–21% over 72 weeks alongside lifestyle changes. Results vary widely between individuals — some lose weight faster, others more slowly. Your prescriber can discuss realistic timelines for you.
What are the common side effects of tizepatide?
Very common side effects include nausea, diarrhoea, vomiting, and constipation, particularly during dose increases. These often improve over time as your body adjusts. Injection site reactions, headache, and fatigue are also common. Serious side effects are rare but include severe stomach pain (possible pancreatitis) — seek urgent medical attention if this occurs.
Can I get tizepatide on the NHS in the UK?
Tizepatide (Mounjaro) is approved by NICE for use within NHS specialist tier 3/4 weight management services. Access requires a GP referral to your local specialist service, though availability and waiting times vary significantly by region. Private prescribing is also available following an online clinical assessment.
How is tizepatide different from Wegovy or Ozempic?
Tizepatide is a dual GIP+GLP-1 agonist, whereas Wegovy (semaglutide) is a GLP-1 agonist only — the dual action may offer greater appetite suppression. Ozempic also contains semaglutide but is licensed only for type 2 diabetes, not weight loss in the UK. Clinical trials suggest tizepatide may produce slightly higher average weight loss, though individual responses vary.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.