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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Can You Stop Mounjaro Cold Turkey?
Stopping Mounjaro abruptly without medical guidance is not recommended, and your prescriber should always be consulted before discontinuing treatment. In the UK, Mounjaro (tirzepatide) is a prescription-only medicine managed through NHS specialist weight management services or private prescribing, and any changes to your treatment should involve your GP or licensed prescriber. This guide explains NHS guidance on safely stopping Mounjaro and what to expect when you discontinue the medication.
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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.
Why You Shouldn't Stop Mounjaro Cold Turkey
Stopping Mounjaro abruptly can lead to several unwanted effects that make gradual discontinuation preferable. Appetite rebound is the most common issue—when you stop the medication suddenly, your appetite may return quickly and intensely, making it difficult to maintain weight loss achieved during treatment. Weight regain can occur rapidly without the medication's appetite-suppressing effects.
Stopping without a plan also removes the structure that supports your ongoing lifestyle changes. The NHS emphasises that weight management medications work alongside reduced-calorie diet and increased physical activity—suddenly stopping both the medication and the behavioural framework can undermine progress. Additionally, if you were taking Mounjaro for metabolic health benefits (beyond weight loss), abrupt cessation may affect blood sugar control or other monitored markers.
- Appetite typically returns within days of stopping
- Weight regain can begin immediately without a structured plan
- Loss of momentum and behavioural support
- Risk of returning to pre-treatment eating patterns
Your NHS prescriber or GP should guide any decision to stop—they will consider your individual circumstances, health goals, and whether continuing, tapering, or switching to alternative support is most appropriate.
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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.
Safe Ways to Stop Mounjaro — NHS Approach
The NHS and UK prescribing guidelines recommend gradual discontinuation rather than stopping suddenly. If you and your prescriber decide Mounjaro is no longer needed, the typical approach involves either completing your current treatment cycle and allowing it to naturally end, or spacing out future doses under medical supervision.
Before stopping, discuss with your GP or specialist prescriber: your current weight and progress, any weight-related health conditions you're managing, your ability to maintain lifestyle changes without medication support, and alternative options if needed. Some patients transition to ongoing support through tier 3 NHS weight management services, which offer behavioural interventions, dietary advice, and monitoring without continuing pharmacological treatment. Document your weight and health metrics using our free progress tracker before and after any change to your treatment plan.
- Inform your prescriber before making any changes
- Plan for ongoing dietary and activity support post-Mounjaro
- Monitor weight changes closely after stopping
- Consider NHS weight management services for ongoing support
- 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 if I stop Mounjaro immediately without telling my prescriber?
Stopping suddenly typically causes rapid appetite rebound and weight regain within days. You may also experience fluctuations in energy levels and blood sugar control if applicable. Always inform your GP or prescriber before discontinuing—they can provide guidance tailored to your health situation and help you maintain progress.
How long after stopping Mounjaro does appetite return?
Most patients report appetite returning within 3–7 days of the last injection, though timing varies individually. Some notice changes within 48 hours, whilst others experience a gradual return over 1–2 weeks. This is why a structured plan for ongoing lifestyle support is important when stopping.
Can I stop Mounjaro and switch to Wegovy instead?
Switching between tirzepatide (Mounjaro) and semaglutide (Wegovy) requires prescriber guidance—they work through different mechanisms, and any transition should be medically managed. Mounjaro is a dual GIP/GLP-1 agonist while Wegovy is GLP-1 only, so direct switching isn't straightforward. Discuss alternative options with your NHS prescriber.
Will I regain all the weight I lost on Mounjaro if I stop?
Weight regain depends on whether you maintain the dietary and activity changes you made during treatment. Some patients sustain significant progress through lifestyle alone; others regain weight gradually. NHS tier 3 services can provide ongoing support to help you maintain results after stopping medication.
Does the NHS recommend stopping Mounjaro after a certain time?
There's no fixed NHS timeframe for Mounjaro treatment duration. Your prescriber will assess whether to continue, pause, or stop based on your progress, health goals, and ability to sustain lifestyle changes. Treatment is personalised—discuss your options at each review appointment with your specialist service or GP.
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.