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 Put Weight On After Stopping Mounjaro?
Many people wonder what happens to their weight after stopping Mounjaro (tirzepatide). Weight regain is common after stopping any weight loss medication, including weekly weight loss injections, because your appetite hormones return to their baseline levels. However, the extent of regain varies between individuals and depends on lifestyle changes made during treatment. This guide explains what to expect and compares the experience between Mounjaro and Wegovy, based on available clinical evidence.
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 Regain After Stopping — Clinical Evidence
Clinical trials for both Mounjaro and Wegovy show that weight regain is a real possibility after stopping treatment. In the SURMOUNT trials for Mounjaro (tirzepatide), participants who achieved significant weight loss on the medication experienced some weight regain after discontinuation — though the extent varied. Similarly, STEP trial data for Wegovy (semaglutide) showed comparable regain patterns.
- Weight regain is not assured — some people maintain losses through lifestyle changes alone
- The more weight lost during treatment, the greater the potential for regain if lifestyle habits revert
- Continued adherence to reduced-calorie diet and physical activity significantly reduces regain risk
- GLP-1 mechanism (Wegovy) works differently from dual GIP+GLP-1 (Mounjaro), but both show similar regain patterns post-treatment
The key difference is that Mounjaro dose titration allows higher final doses (up to 15mg), which may lead to greater initial weight loss — and potentially greater regain risk if lifestyle changes are not maintained.
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.
Mounjaro vs Wegovy — Weight Regain Comparison
Both medications work through appetite suppression and metabolic changes, but there are subtle differences in how regain may occur. Mounjaro's dual GIP and GLP-1 action may support slightly different appetite patterns than Wegovy's GLP-1-only mechanism, but clinical evidence does not show dramatic differences in post-discontinuation regain between the two.
- Mounjaro: dual mechanism may lead to greater initial loss, similar regain pattern post-treatment
- Wegovy: established single mechanism, similar regain outcomes in trials
- Both require ongoing lifestyle support and follow-up care through your GP or specialist
- Neither medication is a permanent solution — both are tools to support behaviour change
The prescription weight loss medication you choose should be based on your GP's assessment of suitability, not on post-discontinuation expectations alone. Use our GLP-1 weight loss calculator to understand projected outcomes during treatment, and our BMI calculator to track your baseline and 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.
Do you definitely put weight back on after stopping Mounjaro?
No — weight regain is not assured. Many people maintain their weight loss through sustained lifestyle changes (diet and exercise). However, some regain is common if eating habits return to pre-treatment patterns, because appetite hormones revert to baseline once the medication stops.
How much weight do people typically regain after stopping Mounjaro?
Clinical trials show variable regain — some participants regain 20–50% of lost weight within months, while others maintain most losses. Individual factors (lifestyle adherence, genetics, comorbidities) determine regain extent. Your GP can help predict your personal risk based on your health profile.
Is weight regain after Mounjaro the same as after Wegovy?
Clinical evidence suggests similar regain patterns between the two medications post-discontinuation. Both are GLP-1-based therapies that work through appetite suppression. Mounjaro's dual mechanism may lead to greater initial loss, but post-treatment regain appears comparable. Your prescriber can discuss individual suitability.
What can you do to prevent weight regain after stopping Mounjaro?
Continue the dietary and exercise habits established during treatment. A sustained calorie deficit, regular physical activity, and ongoing GP support are essential. NHS Weight Management services can provide continued behaviour change support. Consider asking your GP about transition planning before discontinuing treatment.
Why is weight regain common after stopping weight loss injections?
Prescription weight loss medications work by suppressing appetite hormones. Once you stop taking the medication, these hormones return to baseline levels, hunger signals resume, and appetite increases. Without conscious lifestyle maintenance, weight regain is likely. This is why medication is meant to support — not replace — behaviour change.
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.