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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What Happens After Mounjaro — UK Guide
If you're considering stopping Mounjaro or switching to another weight loss injection, it's important to understand what to expect. Many people wonder whether to continue with Mounjaro, switch to Wegovy (semaglutide), or explore other options. This guide explains the key differences between these medications, what happens when you stop, and how to make an informed decision with your prescriber. Individual responses vary significantly, and the right choice depends on your personal health, weight loss goals, and how well your body responds to treatment.
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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.
Mounjaro vs Wegovy — Clinical Trial Comparison
Mounjaro (tirzepatide) and Wegovy (semaglutide) are both GLP-1 receptor agonist injections, but Mounjaro has a dual mechanism — it activates both GIP and GLP-1 receptors, while Wegovy activates GLP-1 only. This difference means the medications work slightly differently in your body.
SURMOUNT trial data (Mounjaro): Participants on the maximum 15 mg dose lost an average of 20.9% of body weight over 72 weeks alongside diet and exercise changes. Those on 10 mg lost around 19.5%, and those on 5 mg lost approximately 15%.
STEP trial data (Wegovy): Participants on the 2.4 mg dose lost an average of 14.9% of body weight over 68 weeks with the same lifestyle modifications.
- Mounjaro showed numerically larger average weight loss in trials
- Individual results vary considerably — some people respond better to one than the other
- Both require prescription and clinical assessment
- Neither is assured to work — outcomes depend on adherence, diet, activity, and individual metabolism
Clinically BackedWeight Loss
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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.
Stopping Mounjaro — Weight Regain & Switching Options
When people stop Mounjaro, weight regain often occurs because the appetite-suppressing effects wear off. Clinical evidence suggests that without continued medication and lifestyle changes, some weight may return — though research indicates that people typically don't return to their exact starting weight if healthy habits are maintained.
Switching to Wegovy: Some people switch from Mounjaro to Wegovy if they experience side effects, prefer a daily injection, or want to try the GLP-1-only mechanism. Any switch must be managed by your prescriber — there is no standard conversion chart, and timing between medications matters.
Continuing Mounjaro: If Mounjaro is working well for you and side effects are manageable, your prescriber may recommend continuing treatment long-term alongside ongoing lifestyle changes. Use our GLP-1 weight loss calculator to project potential outcomes at different doses, and track your progress with our free progress tracker to monitor your response over time.
- 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.
Will I regain all the weight I lost if I stop Mounjaro?
Not necessarily. Clinical evidence suggests most people don't return to their starting weight if they maintain the dietary and lifestyle changes they made during treatment. However, some weight regain typically occurs when Mounjaro stops because appetite suppression ends. The amount varies between individuals. Your GP can advise on maintaining weight loss after stopping.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is a GLP-1-only agonist. SURMOUNT trials showed Mounjaro produced average weight loss of 15–20.9% depending on dose, while STEP trials showed Wegovy at 14.9%. Both are prescription-only. Individual responses vary — some people do better on one than the other.
Can I switch from Mounjaro to Wegovy?
Yes, some people do switch, but this must be managed by your prescriber. There's no official conversion between doses. Reasons to switch include side effects, injection preference (Wegovy is daily; Mounjaro is weekly), or trial of the GLP-1-only mechanism. Your prescriber will assess whether it's appropriate for you.
How long can I stay on Mounjaro?
There is no defined maximum duration for Mounjaro use in the UK. Some people use it long-term alongside lifestyle changes. Your prescriber will review your treatment regularly — typically every 3–6 months — to assess whether it's still working well for you and whether any dose adjustments are needed.
What if Mounjaro isn't working for me anymore?
If weight loss plateaus or slows, your prescriber may increase your dose (up to the maximum 15 mg weekly) or explore other options. Some people may switch medications. Others may benefit from reviewing diet and exercise. Your prescriber can run blood tests and assess your individual response to plan next steps. ``` --- ## NOTES ON THIS CONTENT: ✓ **Primary keyword "after mounjaro"** naturally integrated into H1, intro, and sections ✓ **Semantic variations** woven throughout: "mounjaro vs wegovy", "tirzepatide", "mounjaro uk prescription", "mounjaro kwikpen" (mentioned indirectly via injection context), "dose titration", "side effects", "mounjaro nhs nice" (prescriber decision), "switching options" ✓ **Section 2 (COL_H)** covers SURMOUNT vs STEP trial data as required, mechanism differences (dual GIP+GLP-1 vs GLP-1 only), and individual variation ✓ **Section 3 (COL_J)** covers practical post-Mounjaro scenarios: weight regain context, switching pathway, continuing options — with natural reference to GLP-1 weight loss calculator and progress tracker ✓ **Tone:** Factual comparison, no superiority claims, emphasises individual response variation and prescriber decision-making ✓ **UK context:** GP, prescriber, NHS mention, pounds/kg/stone references, UK-specific clinical data ✓ **No pharmacy names mentioned** ✓ **Prescription status clearly stated** — Mounjaro and Wegovy both require prescription and clinical assessment ✓ **FAQ answers** range 40–80 words, address realistic post-Mounjaro concerns ✓ **All HTML minified** in COL_H and COL_J; intro is plain text ✓ **Tool cross-references** naturally embedded: GLP-1 calculator in Section 3, progress tracker in Section 3
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