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 You Stop Taking Mounjaro?
Yes, you can stop taking Mounjaro at any time, but stopping the tirzepatide injection requires careful planning with your prescriber. Unlike some medications, Mounjaro does not require a gradual dose reduction — you can stop immediately without physical withdrawal. However, weight regain is common after stopping, and your prescriber will discuss the best timing and support for your individual circumstances.
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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.
Stopping Mounjaro vs Wegovy: What the Evidence Shows
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only, once-weekly injections that work through different mechanisms. Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy is a GLP-1-only agonist. Clinical trial data from SURMOUNT (Mounjaro) and STEP (Wegovy) trials show that both medications help with weight loss — averaging 15–clinically studied weight loss with Mounjaro and approximately 15% with Wegovy when combined with diet and activity changes. When stopping either medication, weight regain typically begins within weeks as the appetite-regulating effects wear off. The choice between them depends on individual suitability, assessed during your clinical consultation with a UK prescriber or NHS specialist service.
- Mounjaro: dual mechanism may provide additional appetite suppression for some patients
- Wegovy: single GLP-1 mechanism, longer track record in weight management
- Both require ongoing lifestyle changes to minimise weight regain after stopping
- Neither medication has been shown to prevent weight regain long-term if diet and activity return to pre-treatment levels
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Managing Weight After Stopping — What to Expect
Most clinical evidence suggests that weight regain occurs within 6–12 months of stopping GLP-1 or GIP/GLP-1 medications if lifestyle changes are not maintained. Research shows that patients who lose weight on Mounjaro or Wegovy and then stop the injection typically regain 50–75% of lost weight within one year if diet and physical activity return to previous patterns. Your GP or prescriber can help you plan a maintenance strategy — including sustainable dietary changes, increased physical activity, and potentially use of our free progress tracker to monitor your weight. Some patients may use the medication intermittently or restart at a lower dose if needed, though this requires prescriber guidance. Your prescriber will discuss the most appropriate plan for your individual health goals and circumstances.
- 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 to your body when you stop taking Mounjaro?
When you stop Mounjaro, the appetite-suppressing effects of tirzepatide wear off within days. Your appetite typically returns to baseline levels, gastric emptying returns to normal, and hunger hormones rebalance. Weight regain usually begins within 1–2 weeks and continues unless diet and activity patterns remain changed.
Is there a difference between stopping Mounjaro and stopping Wegovy?
Both work similarly in terms of stopping — no gradual tapering is needed for either. However, Mounjaro's dual GIP/GLP-1 mechanism may provide slightly stronger appetite suppression, so some patients report more noticeable appetite return when stopping. Individual experience varies. Your prescriber can discuss which is more suitable for you.
Can you restart Mounjaro after stopping it?
Yes, Mounjaro can be restarted following a new clinical assessment with your prescriber. You would typically restart at the lowest dose (2.5 mg) and retitrate upwards. Restarting requires a new prescription and clinical assessment — it cannot be done without a prescriber's input.
How do I avoid weight regain after stopping Mounjaro or Wegovy?
Maintain the dietary and activity changes you made whilst taking the medication. Focus on a balanced, reduced-calorie diet and regular physical activity. Use our free progress tracker to monitor your weight and catch early regain. Your GP can also refer you to structured support programmes like NHS weight management services.
Should I stop Mounjaro before trying Wegovy, or can I switch directly?
Any switch between medications must be managed by your prescriber — never switch without clinical guidance. Your prescriber may recommend a brief pause or a direct switch depending on your circumstances. Both medications require a new clinical assessment before switching, as they have different dosing schedules and mechanisms.
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.