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?
If you're taking Mounjaro (tirzepatide) and wondering whether you can pause treatment for a week, the short answer is that it's not recommended without speaking to your prescriber first. Mounjaro is a prescription-only GLP-1 and GIP receptor agonist designed for once-weekly dosing on a consistent schedule. Taking an unplanned week off can affect how the medication works and may impact your weight management progress. Always discuss any changes to your treatment plan with your GP or the prescriber who issued your prescription.
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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.
What Happens If You Miss A Mounjaro Dose?
Missing a single Mounjaro injection by accident is different from intentionally taking a week off. According to the UK prescribing guidance for tirzepatide, if you miss your weekly dose by up to 4 days, you can take it as soon as you remember and continue your normal schedule the following week. However, if more than 4 days have passed since you were due your injection, skip that dose and take your next dose on your normally scheduled day.
The minimum safe time between Mounjaro injections is 72 hours (3 days) — never take a double dose to make up for a missed injection. This spacing is important because Mounjaro works by building up in your system over time. Inconsistent dosing can reduce its effectiveness and may increase side effects like nausea or stomach upset. If you're thinking about skipping a dose intentionally, always contact your prescriber first rather than stopping on your own.
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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.
Why Consistency Matters With Mounjaro Treatment
Mounjaro works most effectively when taken consistently once every 7 days. The medication gradually builds up in your body over the first 4–5 weeks as your dose is titrated upwards — this is why you start on a lower dose and increase every 4 weeks. Taking an unplanned week off disrupts this steady state, which can mean reduced appetite suppression and potentially less weight loss support when you restart.
Additionally, many people experience nausea or other side effects when restarting after a break — your body may need time to readjust. If you're struggling with side effects or want to pause treatment, speak to your GP or prescriber. They may suggest temporarily reducing your dose instead of stopping completely, or they may recommend a proper pause plan. Our free GLP-1 weight loss calculator can help you understand expected outcomes with consistent treatment, so you can make informed decisions with your 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.
Can I deliberately take a week off Mounjaro?
It's not advisable without prescriber guidance. Mounjaro is designed for consistent weekly dosing. Taking an unplanned break can reduce effectiveness and may cause side effects when you restart. If you want to pause treatment, discuss this with your GP or prescriber — they may suggest a safer approach, such as dose reduction rather than a complete break.
What if I accidentally miss my Mounjaro injection?
If you remember within 4 days of your due date, take it as soon as you remember. If more than 4 days have passed, skip that dose and take your next one on your regular scheduled day. Never take a double dose. The minimum safe gap between injections is 72 hours (3 days).
Will one week off Mounjaro affect my weight loss?
A single unplanned week off may reduce appetite suppression temporarily, but one missed dose won't cause significant weight regain. However, if you're considering a longer pause or stopping treatment, this should be discussed with your prescriber. Consistency is important for best results — our progress tracker can help you monitor your outcomes over time.
What should I do if I need to pause Mounjaro for medical reasons?
Contact your prescriber or GP immediately. There may be valid reasons to pause (surgery, severe illness, pregnancy planning). Your prescriber can advise whether a temporary pause is safe and how to safely restart. Don't stop without guidance, as your prescriber may need to adjust your plan.
Is Mounjaro the same as Wegovy?
No. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Both are prescription-only weight management injections in the UK, but they work slightly differently. Mounjaro vs Wegovy comparisons show different average weight losses in clinical trials — your prescriber will recommend which is most suitable for you.
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.