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
Can I Take a Week Off Mounjaro?
Taking a week off Mounjaro (tirzepatide) is generally not recommended, as the medication works best when taken on a consistent weekly schedule. If you need to pause your treatment, it's essential to speak with your prescriber before making any changes. This guide explains what happens if you miss a dose, how to manage your injection schedule safely, and when it's appropriate to take a break from treatment in the UK.
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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.
Understanding Mounjaro Dosing and Missed Doses
Mounjaro is designed as a once-weekly injection, and consistency is key to how the medication works. Each KwikPen contains four weekly doses, so each pen lasts exactly one month. Your prescriber will recommend a specific day each week for your injection—this schedule helps maintain stable levels of tirzepatide in your body and supports the appetite-regulation effects you're relying on.
If you miss a dose within 4 days of when you should have taken it, you can take it as soon as you remember and continue your normal weekly schedule. However, if it's been more than 4 days since your missed dose, you should skip it and take your next injection on your usual scheduled day. Never take a double dose to make up for a missed one. The minimum time between doses should be at least 72 hours (3 days).
Taking a deliberate week off—beyond a missed dose—isn't typically advised without your prescriber's guidance, as stopping and restarting can affect how your body responds to the medication.
Clinically BackedWeight Loss
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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 and Managing Your Prescription
In the UK, you can access Mounjaro through NHS specialist weight management services or private prescription routes. NHS access requires referral to a tier 3 or tier 4 weight management service, which may involve waiting lists. Private access is through a UK-licensed prescriber via an online consultation—if approved, your prescription is dispensed by a GPhC-registered pharmacy.
Regardless of how you access your treatment, your prescriber is your point of contact if you want to pause, reduce, or stop treatment. If you need a break for medical reasons, holiday, or personal circumstances, discuss this with your prescriber first—they may recommend gradually spacing doses or pausing at a specific point in your dose titration cycle rather than stopping abruptly. Regular check-ins about how you're responding to your Mounjaro dose are also important for safe management.
If you're tracking your progress with treatment, our GLP-1 weight loss calculator can help you estimate your expected weight loss trajectory, while our free BMI calculator lets you monitor your health metrics alongside your Mounjaro journey.
- 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.
What happens if I miss a Mounjaro injection?
If you miss a dose within 4 days, take it as soon as you remember and continue your normal weekly schedule. If it's more than 4 days since you missed it, skip it and take your next dose on your usual day. Never take a double dose. If you're unsure, contact your prescriber for guidance.
Can I take a 2-week break from Mounjaro?
Deliberate breaks aren't typically recommended without medical guidance, as stopping and restarting can affect how your body responds. If you need a break for medical or personal reasons, speak with your prescriber—they can advise whether pausing is appropriate or if another approach is better.
Do I need to store my Mounjaro pen differently if I'm taking a break?
Unopened Mounjaro pens must stay refrigerated at 2–8°C until you're ready to use them. Once you've started a pen, it can be kept at room temperature below 30°C for up to 30 days. Store away from heat and direct sunlight.
Can I restart Mounjaro after stopping for a month?
Yes, you can restart after stopping—but your prescriber needs to oversee this. Restarting typically begins at the lowest dose (2.5 mg) again, and you'll work through the titration schedule. Discuss your reasons for stopping and when you want to restart with your prescriber.
What if I want to stop Mounjaro permanently?
You can stop Mounjaro at any time, but inform your prescriber first. Stopping suddenly may cause appetite to return, and your prescriber may want to discuss ongoing weight management support or alternative strategies to help maintain any weight loss you've achieved.
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.