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 If I Stop Taking Mounjaro?
If you stop taking Mounjaro (tirzepatide), weight loss effects gradually reverse over several weeks to months. Your appetite regulation returns to baseline, and weight regain is common without continued lifestyle changes. This happens with all GLP-1 and dual GIP/GLP-1 medications, including Wegovy. The speed and extent of weight return depends on your diet, activity level, and individual metabolism. Always discuss stopping Mounjaro with your GP or prescriber before making changes.
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.
Weight Return Timeline and Mechanism Differences
When you stop Mounjaro, the medication's appetite-suppressing effects wear off within 1–2 weeks, though some effects can persist for 2–3 weeks due to the once-weekly injection cycle. Unlike oral medications, Mounjaro's active form takes time to clear from your system completely. Weight regain typically occurs gradually over 2–3 months if diet and physical activity return to pre-treatment habits.
Mounjaro vs Wegovy comparison: Both are GLP-1-based medications with similar weight rebound patterns when stopped. The key difference is mechanism: Mounjaro is a dual GIP and GLP-1 receptor agonist, while Wegovy is a GLP-1 agonist only. In clinical trials, Mounjaro showed slightly higher average weight loss (up to 20.9% body weight vs Wegovy's approximately 14.9%), but individual results vary significantly. When either medication stops, weight return follows a similar timeline because appetite regulation depends on the medication's continued presence.
The SURMOUNT clinical trial data showed that weight loss achieved on Mounjaro is not "permanent" — it requires ongoing treatment or sustained lifestyle change to maintain. Your GP or prescriber can discuss whether continued treatment or lifestyle-focused weight management is appropriate for your situation.
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.
Preventing Weight Regain After Stopping
The most effective way to prevent weight regain after stopping Mounjaro is maintaining the dietary and physical activity changes you adopted during treatment. Many people find that Mounjaro helps them establish new eating patterns and habits, which can persist even after stopping the medication. However, appetite levels do return to baseline, making it harder to maintain a calorie deficit without ongoing effort.
If you're considering stopping Mounjaro, ask your prescriber about:
- Transitioning to a structured weight management programme
- Working with a dietitian on sustainable eating patterns
- Gradually reducing your dose rather than stopping abruptly
- Whether continuing lower-dose treatment might be beneficial for your health
Use our free GLP-1 weight loss calculator to understand what weight management might look like long-term for you. Our progress tracker can also help you monitor dietary changes and activity levels as you transition off medication.
- 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.
Does weight come back immediately after stopping Mounjaro?
No. Appetite-suppressing effects fade over 1–2 weeks, so weight regain is gradual rather than immediate. Most regain occurs over 2–3 months if diet returns to pre-treatment habits. Individual timelines vary based on lifestyle adherence and metabolism.
Is stopping Mounjaro the same as stopping Wegovy?
The weight rebound pattern is similar because both medications' effects depend on continuous use. Wegovy contains only GLP-1, while Mounjaro is dual GIP+GLP-1, but when either stops, appetite regulation returns to baseline. Results vary individually.
Can I restart Mounjaro if weight returns?
Yes, you can restart Mounjaro following a new clinical assessment with your GP or prescriber. However, restarting requires a new prescription and assessment of your current health status. Discuss with your healthcare provider whether restarting is appropriate for you.
What's the best way to transition off Mounjaro?
Discuss your plan with your prescriber before stopping. Some people benefit from gradually reducing their dose, establishing new eating patterns, and working with a dietitian. Abrupt stopping is possible but may make appetite management harder during the transition period.
Should I stop Mounjaro if I've reached my target weight?
This is a personal decision made with your prescriber. Some people continue lower doses to maintain weight loss; others transition to lifestyle-based management. Your GP can discuss the pros and cons based on your individual health and preferences.
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.