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 Monjuro? UK Weight Management Information
Monjuro is a prescription-only weight management injection licensed in the UK. It's a once-weekly injectable medicine containing tirzepatide, a dual GIP and GLP-1 receptor agonist. This means it works on two natural hormone pathways in the body to help regulate appetite and support weight management alongside a reduced-calorie diet and increased physical activity. If you're exploring healthy weight options, understanding how Monjuro works and whether you might be eligible is an important first step. This UK health guide explains the key facts.
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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 Monjuro Works and What to Expect
Monjuro activates two hormone pathways: the GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) receptors. This dual mechanism may help reduce appetite, decrease food cravings, and support feeling fuller after smaller meals. It also slows how quickly food leaves the stomach, though this effect typically reduces over time with continued use.
In clinical trials (SURMOUNT-1), participants using Monjuro at the maximum 15mg dose lost an average of approximately 20.9% of their body weight over 72 weeks — alongside a reduced-calorie diet and increased physical activity. However, individual results vary significantly, and weight loss is not assured. You can use our free GLP-1 weight loss calculator to explore projected outcomes at different doses. The injectable is administered once weekly using a pre-filled KwikPen device.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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 and NHS Access in the UK
You may be eligible for Monjuro if you have a BMI of 30 or above, or a BMI of 27–29.9 with a weight-related health condition such as type 2 diabetes, prediabetes, high blood pressure, sleep apnoea, or cardiovascular disease. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, eligibility thresholds may start at BMI 27.5 or above due to higher health risks at lower BMI levels.
In the UK, Monjuro is available through NHS specialist tier 3 weight management services (via GP referral) or through private online prescribing following a clinical assessment. NHS access varies significantly by region. Check your BMI and health context using our free BMI calculator, then discuss your options with your GP or a licensed prescriber.
- 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 Monjuro the same as Wegovy?
No. Both are prescription weight management injections, but Monjuro (tirzepatide) is made by Eli Lilly and uses a dual GIP+GLP-1 mechanism. Wegovy (semaglutide) is made by Novo Nordisk and activates GLP-1 only. Clinical trials show Monjuro achieved slightly higher average weight loss (~21% vs ~15%), but individual results vary. Both require prescription and clinical assessment.
Can I get Monjuro on the NHS?
Monjuro is available through NHS specialist weight management services (tier 3), typically accessed via GP referral. However, availability and waiting times vary significantly across UK regions (ICBs). Many people choose private online prescribing instead, which is faster. Your GP can advise which option suits you best.
What are the most common side effects of Monjuro?
Very common side effects include nausea, diarrhoea, vomiting, constipation, and stomach pain — especially when starting or increasing doses. These often improve over time. Less common but serious side effects include severe stomach pain (possible pancreatitis) or allergic reactions. Always report concerning symptoms to your prescriber or GP immediately.
How much does Monjuro cost privately in the UK?
Private Monjuro costs vary by dose and pharmacy, typically ranging from £150 to £350 per month. Costs increase with higher doses. NHS provision is free, but availability is limited. Online prescribing services provide transparent pricing. Always check that any provider is GPhC-registered and offers UK-licensed prescribers.
Does Monjuro work without diet and exercise changes?
No. Monjuro is most effective when combined with a reduced-calorie diet and increased physical activity. Clinical trials showed weight loss only occurred alongside lifestyle changes. Monjuro supports these efforts by helping reduce appetite and cravings, but it's not a substitute for healthy habits. Our free progress tracker can help you monitor both medication use and lifestyle changes.
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.