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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Stopping Mounjaro — What You Need to Know
If you're considering stopping Mounjaro (tirzepatide), it's important to understand what happens after you discontinue the injection and how to make an informed decision. Some people stop Mounjaro because of side effects, others because they've reached their weight loss goals, and some explore alternatives like Wegovy (semaglutide). This guide explains the clinical context, what to expect, and how to discuss stopping with your prescriber. Our GLP-1 weight loss calculator can help you compare potential outcomes between Mounjaro and other options before making changes.
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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 vs Wegovy — Key Differences When Stopping
Mechanism: Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy is a GLP-1-only agonist. This means Mounjaro works on two hormone pathways, whereas Wegovy targets one. Clinical trial data shows Mounjaro achieved approximately 20.9% average body weight loss at the highest dose (15 mg) in the SURMOUNT-1 trial, compared to around 14.9% with Wegovy (semaglutide 2.4 mg) in the STEP-1 trial—though individual results vary significantly.
- Mounjaro: Once weekly, 2.5–15 mg, dual mechanism, requires minimum 4 weeks between dose increases
- Wegovy: Once weekly, 0.25–2.4 mg, single GLP-1 mechanism, standard escalation over 16 weeks
- Clinical context: Both are UK-prescribed weight management injections requiring a prescription and clinical assessment. Switching between them or stopping either should involve your prescriber.
If side effects like nausea, vomiting, or gastroparesis are the reason you're stopping, your prescriber may suggest a dose reduction, a break, or a switch to Wegovy rather than complete cessation.
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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.
What Happens When You Stop — Weight Rebound & Prescriber Support
After stopping Mounjaro, weight regain is common without sustained lifestyle changes. Most clinical trial data shows that stopping GLP-1 or dual-agonist medications typically results in gradual weight return over weeks to months. This doesn't mean you've failed—it reflects how the medication was supporting your appetite regulation and food intake control.
Important steps before stopping: Always discuss discontinuation with your prescriber rather than stopping abruptly. They can assess whether your side effects might resolve with a dose adjustment, or whether switching to Wegovy (which some people tolerate better) is an option. If you're stopping because you've reached your goals, your prescriber can advise on maintenance strategies, including whether restarting at a lower dose or switching medications might help sustain your progress long-term.
- 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.
Will I regain weight if I stop Mounjaro?
Weight regain is typical after stopping without ongoing lifestyle support. Clinical evidence shows most people regain weight gradually over weeks to months as appetite regulation returns to baseline. This is why prescribers often discuss long-term sustainability before stopping. Your GP can advise on maintaining progress through diet and activity changes or considering whether a different medication approach might suit you better.
Can I switch from Mounjaro to Wegovy instead of stopping completely?
Yes—switching is a common option, particularly if side effects are the issue. Approximate dose equivalence suggests Mounjaro 15 mg is similar to Wegovy 2.4 mg, though there's no official conversion chart. Any switch must be managed by your prescriber, who will assess whether Wegovy's single GLP-1 mechanism might work better for you than Mounjaro's dual action. Use our GLP-1 weight loss calculator to compare projected outcomes.
How long after stopping Mounjaro before I notice appetite changes?
Appetite typically begins returning within days to a week after your last injection, as the medication leaves your system. Most people notice fuller hunger sensations and stronger food cravings within 1–2 weeks. This is why post-medication support—whether through diet structure, increased activity, or medication alternatives—matters for sustaining weight loss gains.
Is it safe to stop Mounjaro without tapering?
Unlike some medications, Mounjaro doesn't require a tapering schedule—you can stop after your last injection. However, you should always inform your prescriber before stopping so they can discuss weight management strategies going forward and rule out any underlying reasons (like side effects) that might be manageable with adjustments instead.
What's the difference between stopping and pausing Mounjaro?
Stopping means discontinuing completely; pausing means taking a break and potentially restarting later. Some people pause Mounjaro to manage side effects, allowing their system to reset, then restart at a lower dose. This is a prescriber decision and requires clinical guidance. Pausing is different from stopping—discuss your goals clearly with your prescriber to find the best approach.
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.