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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What Happens When You Come Off Mounjaro?
Stopping Mounjaro (tirzepatide) is a decision that should be made with your prescriber, as weight regain and appetite changes can occur after stopping treatment. Understanding what to expect when you come off Mounjaro—and how it compares to discontinuing Wegovy—can help you plan your weight management strategy. Both medications work differently, so their effects after stopping differ too. This guide covers the realistic outcomes, timeline, and practical next steps for UK adults considering ending Mounjaro treatment.
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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.
How Mounjaro and Wegovy Differ When Stopping Treatment
Mounjaro and Wegovy are both prescription-only weight management injections, but they work through different mechanisms. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, activating two hormone pathways, while Wegovy (semaglutide) is a GLP-1-only agonist. This difference affects how quickly appetite regulation returns after stopping.
Clinical trial data shows that when patients discontinued Mounjaro in the SURMOUNT trials, weight regain typically began within 2–4 weeks. Similarly, when Wegovy patients (from the STEP trials) stopped treatment, rebound weight gain occurred. However, the timeline and intensity can vary between individuals. Some people regain weight quickly; others stabilise. Neither medication is designed as a permanent treatment—both work best alongside sustained lifestyle changes including reduced-calorie eating and regular physical activity.
- Mounjaro's dual mechanism may affect appetite regulation differently than Wegovy's single GLP-1 pathway
- Weight regain risk is present with both medications after stopping
- Individual response varies significantly
- Lifestyle habits established during treatment are key to long-term weight maintenance
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.
Planning Your Transition: Prescriber Support and Lifestyle Strategy
If you're considering coming off Mounjaro, discuss your decision with your prescriber rather than stopping suddenly. They can help you assess whether discontinuation is right for you, plan a gradual transition, and reinforce dietary and activity strategies to minimise weight regain. Neither Mounjaro nor Wegovy should be stopped abruptly without medical guidance.
Use your time on treatment to establish sustainable habits: focus on balanced nutrition, regular physical activity, and consistent portion control. Many people find that tracking progress with a free progress tracker helps them maintain accountability after stopping medication. Your prescriber may also discuss whether restarting treatment or switching to alternative approaches would be suitable if weight regain becomes significant. The decision to stop, continue, or switch is always personal and based on your health goals, circumstances, and clinical assessment.
- 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 just stop taking Mounjaro without telling my GP?
No—you should always inform your prescriber before stopping Mounjaro. They can assess whether it's safe to discontinue, advise on tapering if needed, and help you plan strategies to minimise weight regain. Stopping suddenly without support increases the risk of rapid rebound weight gain and loss of appetite regulation benefits.
How quickly do you regain weight after stopping Mounjaro?
Weight regain typically begins within 2–4 weeks of stopping Mounjaro, though the speed and amount vary significantly between individuals. Some people regain weight quickly; others stabilise if they maintain the dietary and activity habits developed during treatment. Your prescriber can advise based on your individual situation.
Is stopping Wegovy different from stopping Mounjaro?
Both carry weight regain risk, but the mechanism is slightly different. Mounjaro's dual GIP+GLP-1 action and Wegovy's GLP-1-only action may affect appetite regulation differently. However, individual responses vary more than medication type. Your prescriber can advise which factors matter most for you.
What should I do to prevent weight regain after stopping?
Focus on sustaining the healthy habits you developed during treatment: balanced nutrition, regular physical activity, portion control, and consistent self-monitoring. Many people find that tracking their weight and progress regularly helps maintain accountability. Your GP or a dietitian can provide personalised guidance.
Can I restart Mounjaro if I regain weight after stopping?
Yes, if clinically appropriate, you may be able to restart Mounjaro following another clinical assessment. This is a conversation to have with your prescriber. Some people find a phased approach—with breaks and restarts—works for their long-term weight management strategy. Others prefer continuous treatment.
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.