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
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1mg Wegovy Compared to Mounjaro — NHS Guide
At 1mg, Wegovy (semaglutide) and Mounjaro (tirzepatide) represent different stages of dose escalation within the NHS weight management pathway. Wegovy operates as a GLP-1 receptor agonist, whilst Mounjaro is a dual GIP and GLP-1 agonist — meaning they work through different biological mechanisms. Both medications require NHS referral to specialist tier 3 weight management services in the UK, though access varies significantly by region. This guide explains the differences between these doses, NHS eligibility criteria, and how prescribers choose between them based on individual patient health profiles.
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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.
NHS Eligibility and Specialist Services Access
Both Wegovy and Mounjaro are prescription-only medicines available through NHS specialist weight management services following NICE guidance. Eligibility requires a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, hypertension, or cardiovascular disease. For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds apply — typically from 27.5 kg/m² onwards due to increased health risks at lower BMI levels.
NHS access occurs through tier 3 specialist services, not standard GP prescription. Your GP refers you to a multidisciplinary weight management team, which conducts a comprehensive assessment. This assessment determines which medication is most appropriate. At 1mg, Wegovy represents the third escalation step (weeks 9–12), whilst equivalent Mounjaro dosing would be around 5mg (first maintenance dose). Prescribers assess individual factors including kidney function, gastrointestinal history, and previous medication response when selecting between tirzepatide and semaglutide.
NHS availability varies by integrated care board (ICB). Some regions have dedicated tier 3 services with rapid access; others have substantial waiting lists. Contact your local ICB to understand availability in your area.
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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.
NHS vs Private Access — Cost and Timeline Differences
On the NHS, both Mounjaro and Wegovy are available at no cost to eligible patients (other than standard prescription charges if applicable in England). However, NHS access typically involves a waiting period ranging from weeks to many months, depending on regional capacity. Once accepted into a tier 3 service, treatment is monitored regularly by specialist teams, including regular weight and health outcome assessments.
Private access via a UK-licensed prescriber and GPhC-registered pharmacy offers faster initiation (often within days) but requires payment ranging from approximately £129–£320 per month depending on dose. Private prescribers assess eligibility using the same NHS criteria but can initiate treatment without NHS referral pathways. For 1mg Wegovy or equivalent Mounjaro dosing, clarify exact costs with your chosen provider, as pricing varies. Many patients use private routes whilst waiting for NHS specialist assessment.
- 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 1mg Wegovy equivalent to any Mounjaro dose?
Approximate equivalence suggests 1mg Wegovy is similar to 5mg Mounjaro in terms of glucose control effect, though they work differently — Wegovy through GLP-1 alone, Mounjaro through dual GIP and GLP-1 pathways. There is no official NHS conversion chart. Any switch between medications must be managed by your prescriber based on your individual response and tolerability.
Can I get Mounjaro on the NHS in the UK?
Yes, Mounjaro (tirzepatide) is NICE-approved and available through NHS tier 3 specialist weight management services. You must be referred by your GP to a multidisciplinary weight management team. NICE recommends tirzepatide as an option for eligible adults with a BMI of 30 or above, or 27–29.9 with weight-related comorbidities. Access varies significantly by region.
Which is more effective — 1mg Wegovy or Mounjaro?
Clinical trial data shows both support meaningful weight loss alongside diet and physical activity. Mounjaro demonstrated slightly higher average weight loss (around 20.9% body weight at maximum dose) compared to Wegovy (around 14.9% body weight). Individual results vary considerably. Your prescriber will recommend the most suitable based on your health profile, previous medication response, and medical history.
How long is the NHS waiting list for Mounjaro or Wegovy?
Waiting times vary substantially across UK regions. Some specialist tier 3 services have waiting lists of 3–6 months; others experience longer delays. Contact your local integrated care board (ICB) or ask your GP about typical waiting times in your area. Private options can be accessed faster if NHS waiting is a concern, though this involves direct payment.
Will my NHS prescription cost change between 1mg Wegovy and Mounjaro?
On the NHS, if you are exempt from prescription charges, both medications cost nothing. If you pay for prescriptions in England, each prescription is typically one standard charge regardless of dose or medication type. Private costs differ — clarify exact pricing with your provider if using private access routes.
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