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 Stop Taking Mounjaro?
When you stop taking Mounjaro (tirzepatide), your body returns to its natural hunger and appetite signals over several weeks. Many people experience weight regain if lifestyle changes aren't maintained, though the timeline and amount vary significantly between individuals. Understanding what to expect after stopping — and how it compares to stopping Wegovy — can help you plan your weight management strategy with your prescriber.
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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 Your Body Responds After Stopping Mounjaro
When you stop a Mounjaro KwikPen injection, the tirzepatide in your system gradually clears over approximately 4–5 weeks. During this period, your appetite and hunger signals gradually return to their pre-treatment levels. The dual GIP and GLP-1 effects that helped suppress appetite and regulate blood sugar fade as the medication leaves your body.
- Week 1–2: Appetite may begin to increase noticeably; nausea and reduced appetite side effects typically improve
- Week 3–5: Hunger signals normalise; fullness from meals returns to baseline
- Weeks 6+: Natural appetite regulation fully restored; weight regain risk increases if diet isn't maintained
Weight regain is common but not inevitable. Clinical data shows that without continued lifestyle changes, many people regain 50–80% of lost weight within 1–2 years after stopping. However, individuals who maintain reduced-calorie eating and physical activity often keep most or all of their weight loss. Your GP or prescriber can discuss strategies to minimise regain when stopping treatment.
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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.
Mounjaro vs Wegovy: Stopping and Rebound Differences
Both Mounjaro and Wegovy (semaglutide) follow a similar rebound pattern after stopping — appetite returns, weight may regain — because both activate appetite-suppressing pathways. However, the underlying mechanism differs: Mounjaro is a dual GIP and GLP-1 agonist, while Wegovy is GLP-1-only. This means Mounjaro may have produced a stronger appetite-suppressing effect during treatment, and some people report slightly more noticeable hunger increase after stopping.
Clinical trial data shows similar weight regain timelines for both medications when stopped. The key factor is not which medication you used, but whether you've established sustainable eating and exercise habits that persist after stopping. Your prescriber can assess which medication suits your health profile during initial Mounjaro dose titration or if switching between treatments.
Whether you're considering stopping Mounjaro, switching to Wegovy, or planning long-term treatment, your decision should be made with your prescriber. Mounjaro and Wegovy are both UK prescription-only medicines — available through NHS specialist weight management services or private online prescribing following a clinical assessment. The choice between them, and the decision to stop or continue, depends on your individual health, weight loss goals, and ability to maintain lifestyle changes. Use our free BMI calculator and GLP-1 weight loss calculator to track your progress and discuss results with your GP before making any changes to treatment.
- 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 all the weight I lost after stopping Mounjaro?
Not necessarily. Weight regain depends on your lifestyle after stopping. Clinical data shows people regain 50–80% of weight without sustained changes, but those maintaining reduced calories and activity often keep most weight off. Your GP can help you plan strategies to minimise regain.
How quickly does appetite come back after stopping Mounjaro?
Appetite typically begins returning within 1–2 weeks as tirzepatide clears your system. By week 4–5, hunger signals usually return to baseline. Individual timelines vary — some people notice changes within days, others take several weeks.
Is stopping Mounjaro the same as stopping Wegovy?
The rebound effect is similar, but the mechanisms differ. Mounjaro is a dual GIP+GLP-1 agonist, while Wegovy is GLP-1-only. Both show comparable weight regain timelines if lifestyle isn't maintained. Your prescriber can advise which suits you best.
Can I restart Mounjaro if I've stopped it?
Yes, Mounjaro can be restarted following a clinical assessment with your prescriber. You would typically restart at a lower dose and titrate up again. Your previous response to the medication can help inform dosing decisions.
What should I do before stopping Mounjaro?
Discuss stopping with your prescriber first. Plan strategies to maintain reduced-calorie eating and physical activity. Consider whether switching medications rather than stopping might suit your goals better. Your GP or specialist can provide personalised guidance based on your health and weight loss progress.
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.