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
What Happens When You Stop Mounjaro?
Stopping Mounjaro is a decision that requires careful planning with your prescriber. Unlike some medications, Mounjaro doesn't cause traditional "withdrawal" symptoms, but stopping the injection may result in rebound weight gain and return of appetite. This guide explains what to expect when discontinuing tirzepatide in the UK context, whether you're stopping via NHS tier 3 services or through private prescription. Understanding the science behind stopping helps you make informed decisions with your GP or prescriber.
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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.
How Mounjaro Works and What Happens When You Stop
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist that actively suppresses appetite and regulates blood sugar while you're taking it. Once you stop injecting, the medication leaves your system relatively quickly—typically within 1–2 weeks—as tirzepatide has a half-life of around 5 days. Important: This is not true withdrawal like opioid or alcohol dependence. Instead, your body's natural hunger and appetite signals return as the medication effect wears off.
- Appetite returns: GLP-1 and GIP pathways stop being artificially activated, so you feel hungry again
- Weight regain risk: Without the appetite suppression and the reduced-calorie diet it supported, weight gain is common if eating patterns revert
- No dangerous physical withdrawal: You won't experience tremors, sweating, or severe physical symptoms from stopping Mounjaro itself
- Timing matters: Gradual dose reduction (rather than abrupt stopping) is recommended by prescribers to help your body adjust
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.
Managing Weight After Stopping Mounjaro — NHS and Private Guidance
If you're stopping Mounjaro through NHS tier 3 weight management services, your specialist team will provide a tailored plan to maintain weight loss through lifestyle changes. Clinical data shows that most weight regain occurs within 6–12 months of stopping GLP-1 medications if eating and activity patterns don't change. To minimise rebound weight gain: maintain the calorie deficit and exercise habits you developed while on the injection, use our free GLP-1 weight loss calculator to reset realistic goals without medication, track your progress with our free progress tracker, and return to your GP if weight gain accelerates or you need re-evaluation for restarting treatment. Many people benefit from longer-term medication use rather than stopping abruptly—discuss this with your prescriber before making a final decision.
- 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 get withdrawal symptoms if I stop taking Mounjaro?
No. Mounjaro doesn't cause traditional withdrawal like opioids or benzodiazepines. You won't experience tremors, sweating, or severe physical distress. However, appetite and hunger signals return as tirzepatide leaves your system, which can feel uncomfortable. Your prescriber may recommend gradual dose reduction rather than stopping abruptly.
How quickly does weight come back after stopping Mounjaro?
Weight regain varies greatly between individuals. Clinical evidence suggests most regain occurs within the first 6–12 months if eating and activity patterns return to pre-treatment levels. Using our free BMI calculator and weight converter helps track changes. Many people maintain weight loss if they continue the reduced-calorie diet and exercise habits developed while on the injection.
Can I restart Mounjaro after stopping it?
Yes, in most cases you can restart Mounjaro, but this requires a new clinical assessment with your prescriber—whether through NHS tier 3 services or private prescription. Restarting is not automatic. You'll need to re-establish that you meet eligibility criteria and that the medication is still appropriate for your health situation.
What's the difference between stopping Mounjaro and stopping Wegovy?
Both are GLP-1-based medications with similar withdrawal patterns—no dangerous physical withdrawal, but return of appetite and rebound weight gain risk. Mounjaro is a dual GIP and GLP-1 agonist while Wegovy is GLP-1 only, so the mechanism differs slightly, but stopping either requires the same careful planning and lifestyle support from your prescriber.
Should I stop Mounjaro gradually or all at once?
Gradual dose reduction is generally recommended by prescribers rather than abrupt stopping. This helps your body adjust gradually to returning appetite signals. However, your specific prescriber—whether NHS or private—will advise based on your individual circumstances. Never stop prescription medication without discussing it with your GP or licensed prescriber first.
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.