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?
When you stop taking Mounjaro (tirzepatide), your body adjusts back to its natural hormone levels. Side effects from the injection itself typically resolve within days or weeks, but weight regain and metabolic changes can occur over months. This guide explains what to expect after stopping, based on NHS and clinical evidence, to help you plan your weight management journey safely with your GP or prescriber.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Understanding Mounjaro Withdrawal and Side Effect Changes
Mounjaro is a dual GIP and GLP-1 receptor agonist that works by mimicking natural hormones controlling appetite and blood sugar. When you stop taking it, these artificial signals stop, and your body returns to baseline.
- Injection site side effects resolve quickly — redness, bruising, or pain at injection sites disappear within a few days as the medication clears your system
- Gastrointestinal side effects ease gradually — nausea, diarrhoea, constipation, and stomach discomfort typically improve over 1–4 weeks as your digestive system readjusts
- Appetite returns — hunger and food cravings often return within days, which can be challenging psychologically after months of reduced appetite
- Weight regain is common — without continued medication and lifestyle changes, many people regain weight over 6–12 months, though not always to baseline
- Blood sugar rises — if you have diabetes or prediabetes, blood glucose levels may increase, requiring GP monitoring
The NHS emphasises that stopping Mounjaro should be planned with your healthcare provider, not done suddenly, to manage these changes safely.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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 the Stop: NHS Guidance and What to Expect
Your GP or specialist will advise on the safest way to stop, especially if you have type 2 diabetes or prediabetes. No tapering schedule is required — you can stop at any time — but planning ahead helps you prepare emotionally and practically.
To reduce weight regain after stopping, the NHS recommends maintaining the dietary and physical activity habits you built while on Mounjaro. Use our free progress tracker to log your ongoing weight and monitor trends, and our BMI calculator to check your healthy weight range for your height. Many people benefit from continuing with a reduced-calorie diet, increasing exercise, and addressing eating behaviour patterns. Some individuals may choose to restart Mounjaro or try an alternative GLP-1 medication like Wegovy (semaglutide) if appropriate — your prescriber can discuss whether this suits your health goals.
- 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.
How quickly do Mounjaro side effects stop after my last injection?
Injection site reactions and gastrointestinal side effects typically resolve within 1–4 weeks. Nausea usually improves within days, whilst appetite typically returns within 3–7 days. However, weight regain can continue over months if lifestyle habits don't support weight maintenance, so prepare beforehand with your GP.
Will I regain all the weight I lost on Mounjaro after stopping?
Weight regain is common but not inevitable. Clinical evidence shows that maintaining the calorie deficit, dietary changes, and physical activity you adopted while on Mounjaro helps prevent full regain. Many people stabilise at a weight higher than whilst on medication but lower than baseline, especially with sustained lifestyle changes.
Is it dangerous to stop Mounjaro suddenly?
No — there is no medical danger to stopping suddenly. However, planning your stop with your GP is recommended, especially if you have diabetes or are on other medications. Your prescriber can discuss managing increased appetite, monitoring blood sugar, and strategies to prevent rapid weight regain.
What should I tell my GP before stopping Mounjaro?
Inform your GP or prescriber that you plan to stop so they can check your blood sugar control (if diabetic), review any other medications that may need adjusting, and help you plan your post-Mounjaro weight management strategy. They can also discuss whether restarting or switching to another GLP-1 medication is appropriate for your situation.
Can I restart Mounjaro if I stop and then regain weight?
Yes — if appropriate, your prescriber can prescribe Mounjaro again. However, you'll need to restart from the lowest dose (2.5 mg) and titrate upwards as before. Discuss with your GP whether restarting Mounjaro, trying an alternative weight loss injection, or focusing on lifestyle changes alone best suits your health goals.
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.