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
When Should You Stop Taking Mounjaro?
Deciding when to come off Mounjaro is a personal decision made with your prescriber, not something you should do alone. Some people stop after reaching their weight loss goal, others continue long-term to maintain results. Unlike short-term diets, weight loss medications like tirzepatide (Mounjaro) and semaglutide (Wegovy) work differently — stopping them often leads to weight regain without ongoing lifestyle support. Your GP or prescriber will assess whether continuing, pausing, or stopping is right for your individual health situation based on your results, side effects, and overall wellbeing.
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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.
Mounjaro vs Wegovy: Trial Data and Discontinuation
Both Mounjaro (tirzepatide) and Wegovy (semaglutide) are GLP-1 receptor agonists approved for weight management in UK adults, though Mounjaro also activates GIP receptors, giving it a dual mechanism. In the SURMOUNT clinical trials, Mounjaro achieved average weight loss of 20.9% at the maximum 15 mg dose, while Wegovy achieved approximately 15% in STEP trials — both alongside reduced-calorie diet and increased activity. Neither medication is "temporary" in the traditional sense; they're typically continued as long as they're helping and causing no significant problems.
- Mounjaro kwikpen users in trials who stopped treatment experienced weight regain, highlighting that benefits require ongoing use
- Wegovy showed similar patterns — discontinuation led to gradual weight rebound
- Both require a UK prescription and regular prescriber reviews to monitor effectiveness and side effects
- The choice between them depends on individual response, not inherent superiority
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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.
When Your Prescriber Might Suggest Stopping
Your GP or specialist may recommend stopping or pausing Mounjaro if: you're experiencing serious or intolerable side effects, you've developed a medical condition making it unsuitable (such as severe pancreatitis), you're planning pregnancy, or you're not showing meaningful weight loss after several dose increases. Some people choose to stop after reaching a target weight, though maintaining a lower weight without medication is challenging. Mounjaro dose titration typically takes 16–20 weeks to reach maximum effect, so your prescriber won't suggest stopping before giving the medication adequate time to work. Stopping should always be a discussion, not a sudden decision — abrupt discontinuation can lead to rapid weight regain and side effect rebound. If you're considering stopping, discuss your reasons with your prescriber first; there may be alternatives like dose reduction or lifestyle intensification.
- 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 my weight if I stop Mounjaro?
Weight regain is common after stopping. Clinical trials showed that participants who discontinued Mounjaro regained weight over time. Most people need ongoing medication or very strong lifestyle habits to maintain losses long-term. Your prescriber can discuss strategies to minimise regain, including continued dietary changes and activity.
Can I switch from Mounjaro to Wegovy instead of stopping?
Yes, switching is possible and sometimes recommended if you're experiencing side effects or not achieving goals. Mounjaro and Wegovy use different mechanisms (Mounjaro is dual GIP+GLP-1, Wegovy is GLP-1 only), so response differs between individuals. Any switch must be managed by your prescriber to ensure safe transition and appropriate dosing.
Should I stop Mounjaro before trying to get pregnant?
Yes, Mounjaro is not recommended during pregnancy. You should stop at least 2 months before trying to conceive if possible, though discuss timing with your GP. Other contraception methods may be needed initially. After birth, breastfeeding is also not recommended with Mounjaro, so discuss family planning with your prescriber.
How do I know if Mounjaro is working well enough to continue?
Your prescriber will assess this at regular reviews, typically every 4–12 weeks. They'll look at weight loss progress, how you feel, side effects, and any changes in weight-related health conditions like blood pressure or blood sugar. Use our free GLP-1 weight loss calculator to track projected progress alongside your prescriber's assessments.
Is it safe to stop Mounjaro suddenly?
Stopping suddenly is not dangerous in the medical sense, but it can lead to rapid weight rebound and temporary side effect changes. A planned, gradual approach discussed with your prescriber is better. They may suggest tapering doses or transitioning to lifestyle-only management with structured support rather than abrupt cessation.
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.