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
Do You Gain Weight Back After Stopping Mounjaro?
Many people wonder whether they'll regain weight after stopping Mounjaro. The short answer is: weight regain is possible, but not inevitable. Clinical evidence shows that without continued lifestyle changes or ongoing treatment, some people do regain weight after stopping. However, the amount regained varies significantly between individuals depending on diet, activity levels, and metabolic factors. Understanding what happens after stopping treatment helps you plan a realistic long-term weight management strategy with your GP.
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.
What Research Shows About Weight Regain After Stopping Mounjaro
Clinical trials and real-world data indicate that weight regain after stopping a GLP-1 or GIP/GLP-1 medication like Mounjaro is common but not universal. In the SURMOUNT trial, participants who continued Mounjaro maintained their weight loss, while those who stopped the medication experienced gradual weight regain. However, research also shows that people who had successfully built sustainable eating habits and increased physical activity during treatment were more likely to maintain a larger proportion of their weight loss.
- Approximately 50–80% of weight lost can be regained within 1–2 years if no lifestyle changes are maintained
- Weight regain tends to happen gradually, not suddenly, after stopping treatment
- Individual outcomes vary based on genetics, diet, exercise habits, and overall metabolic health
- A weekly weight loss injection like Mounjaro works by reducing appetite and food cravings — these effects fade once you stop taking it
- Your prescriber and GP can help you develop a post-treatment plan to minimise regain
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.
How to Maintain Weight Loss After Stopping Mounjaro
The best way to avoid significant weight regain is to use your time on Mounjaro to build sustainable lifestyle habits that will work long-term. This means establishing regular physical activity, mindful eating patterns, and realistic dietary changes before you stop treatment. Work with your prescriber to plan your exit strategy — some people may benefit from a gradual dose reduction rather than stopping abruptly. Keep using tools to monitor progress, such as a progress tracker to log your weight and habits. Stay in contact with your GP for ongoing support, as they can discuss whether continuing treatment, a lower maintenance dose, or alternative weight management strategies might suit your long-term 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.
Is weight regain after stopping Mounjaro assured?
No, weight regain is not assured. Many people maintain most of their weight loss if they continue the lifestyle changes they built during treatment — regular exercise, balanced nutrition, and portion control. However, research shows that without these habits, gradual regain is likely for most people.
How quickly do you regain weight after stopping Mounjaro?
Weight regain typically happens gradually over weeks and months, not immediately. The pace depends on individual metabolism and lifestyle. Some people notice changes within a few weeks; others take several months to regain significant weight.
Can you restart Mounjaro if you regain weight?
Yes, you can restart Mounjaro if clinically appropriate. Your prescriber will reassess your eligibility and health status. Some people use Mounjaro intermittently — taking it for periods then stopping and restarting based on their weight management needs.
What's the difference between stopping Mounjaro and Wegovy?
Both are prescription-only weight loss injections with similar weight regain patterns after stopping. Mounjaro is a dual GIP/GLP-1 injection; Wegovy is a GLP-1-only injection. Individual response varies, but the principle is the same — maintaining weight loss after stopping requires sustained lifestyle changes.
Should I talk to my GP before stopping Mounjaro?
Yes, absolutely. Always discuss stopping Mounjaro with your prescriber. They can help you plan a realistic exit strategy, discuss whether a gradual dose reduction is appropriate, and provide support for maintaining weight loss long-term. Your GP can also help you access ongoing weight management support through NHS or other services.
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.