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
How Many Clicks Per Dose With Mounjaro vs Wegovy?
The Mounjaro KwikPen and Wegovy auto-injection pen work differently when it comes to clicks per dose. Mounjaro uses a single click to inject each dose, whilst Wegovy requires multiple clicks depending on your strength. Understanding these mechanics helps you feel confident with your injection routine. Both are prescription-only weight management injections licensed in the UK, and both use pre-filled pens designed for ease of use at home.
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Calculate Your BMI Instantly
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.
Mounjaro KwikPen vs Wegovy Auto-Injector Mechanics
Mounjaro KwikPen: The Mounjaro device is designed for simplicity — you dial your dose on the pen (which your prescriber will specify), then press the injection button once. A single click administers the full weekly dose. The pen automatically locks after use, preventing accidental reinjection. Each KwikPen contains exactly 4 weekly doses, so you receive 4 pens per month.
Wegovy auto-injector pen: Wegovy uses a different mechanism. The auto-injector pen does not require a UK pharmacy clicking in the traditional sense — you simply press the pen against your skin and it self-injects automatically. However, the device may produce a clicking sound during injection as the spring mechanism releases, which can feel different from the Mounjaro experience.
Key difference: Mounjaro offers a single, intentional click for dose control. Wegovy's auto-mechanism is fully automatic with no user-controlled clicking. Both pens are pre-filled and designed to be used once weekly. Your prescriber will discuss injection technique during your clinical assessment, and both manufacturers provide detailed guides with your first prescription.
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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.
SURMOUNT vs STEP: Clinical Evidence and Individual Suitability
Clinical trials showed different efficacy profiles. The SURMOUNT-1 trial (Mounjaro) demonstrated average weight loss of approximately 20.9% at the maximum 15 mg dose over 72 weeks. The STEP-1 trial (Wegovy) showed average weight loss of approximately 14.9% at the 2.4 mg dose over 68 weeks. However, individual results vary significantly, and these are population averages — your personal outcome depends on many factors including adherence, lifestyle changes, and your body's response.
Both medications work through GLP-1 pathway activation, but Mounjaro is a dual GIP and GLP-1 agonist (dual mechanism), whilst Wegovy is a GLP-1 agonist only (single mechanism). This mechanistic difference may explain why some users experience better results with Mounjaro, whilst others respond well to Wegovy. Your prescriber will assess which is more suitable for you based on your health profile, previous medication responses, and personal circumstances. Neither medication is universally "better" — suitability is individual.
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only and require a clinical assessment before being prescribed. You cannot choose between them purely based on injection mechanics — your GP or licensed prescriber will determine eligibility based on your BMI, health conditions, and medical history. Use our free GLP-1 weight loss calculator to explore projected outcomes at different doses, and discuss your options with your prescriber. Both injections work best alongside a reduced-calorie diet and increased physical activity, not as standalone treatments. Your prescriber will also discuss storage (both require refrigeration when unopened), injection site rotation, and what to do if you miss a dose.
- 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.
Does Mounjaro hurt more because it requires a click?
No. Mounjaro's single-click mechanism is not more painful than Wegovy's auto-injection. Both use fine needles (29 gauge) and are designed to minimise discomfort. Pain perception varies between individuals and injection sites, not the device type. Most users report minimal discomfort with either injection.
Can I switch from Mounjaro to Wegovy based on the injection style?
Injection mechanics alone should not drive medication choice. Both require clinical assessment and prescription. If you wish to switch medications, your prescriber must assess suitability. Approximate dose equivalence exists (10 mg Mounjaro ≈ 1.7 mg Wegovy), but any switch must be medically managed.
Is Mounjaro a single click safer than Wegovy's auto-mechanism?
Both pens are equally safe when used correctly. Mounjaro's single-click design gives users intentional control. Wegovy's automatic mechanism removes potential for user error. Safety depends on following instructions from your prescriber and the manufacturer — not the device type itself.
How often do I need to use the Mounjaro pen if it has clicks built in?
You use the Mounjaro KwikPen once per week. Each pen contains 4 weekly doses. You dial your prescribed dose strength, inject once (one click), then discard. You do not click multiple times per week — it is one injection, one click, per week.
What if I'm worried about injections — should I choose Mounjaro or Wegovy?
Needle anxiety is common and real. Both Mounjaro and Wegovy use fine, short needles. Many users find the weekly frequency (vs daily alternatives like Saxenda) easier to manage. Your prescriber can discuss anxiety management strategies. Your personal comfort matters, but medication suitability comes first — discuss concerns during your clinical assessment.
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.