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
When Do You Stop Losing Weight on Mounjaro?
Weight loss on Mounjaro (tirzepatide) typically continues as long as you remain on the medication and maintain a reduced-calorie diet and physical activity. However, weight loss is not linear — most people experience plateaus at different points during their treatment. Understanding how Mounjaro works, when weight loss may slow, and what affects your results can help you set realistic expectations and work with your prescriber on the best approach for your individual needs.
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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.
How Weight Loss Progresses on Mounjaro
Weight loss on Mounjaro follows a pattern similar to other weekly weight loss injections. Most people see noticeable changes in the first 4–12 weeks as the medication takes effect and appetite regulation improves. The dose titration schedule (starting at 2.5 mg and escalating every 4 weeks) means that weight loss often accelerates as you reach higher maintenance doses. Clinical trials showed that participants on Mounjaro lost an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly. Weight loss typically continues throughout treatment as long as you maintain a reduced-calorie diet and increased physical activity. However, weight loss is not constant — most people experience periods of faster loss followed by plateaus, which is completely normal. Your prescriber can help assess whether your dose needs adjustment if weight loss slows significantly after an initial period of good progress.
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.
When Weight Loss May Plateau or Slow
Weight loss plateaus are a natural part of any weight management journey. On Mounjaro, plateaus may occur because your body adapts to the lower calorie intake, your appetite regulation stabilises, or you reach a point where your current lifestyle is balanced. Plateaus typically last 2–8 weeks and do not mean the medication has stopped working. Other factors affecting weight loss include sleep quality, stress levels, underlying medical conditions, medications you take alongside Mounjaro, and hormonal changes. If you've been on a stable Mounjaro dose for several weeks and weight loss has stalled, discuss with your prescriber whether a dose increase or lifestyle adjustment might help. Some people find that refreshing their diet or exercise approach reignites progress. Remember that even if weight loss stops, maintaining your current weight is still a positive health outcome and reduces ongoing health risks.
- 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 lose weight continuously on Mounjaro?
Weight loss is not linear. Most people experience periods of faster loss followed by plateaus, which is normal and expected. You may lose weight steadily for several weeks, then plateau for 2–8 weeks before losing again. Use our GLP-1 weight loss calculator to estimate potential progress at different doses.
What happens if my weight loss stops on Mounjaro?
A plateau does not mean Mounjaro has stopped working. Your body has adapted to the calorie deficit. A dose increase, dietary adjustment, or exercise changes may help restart progress. Discuss with your prescriber if you've been stable for 8+ weeks without weight loss.
How long does weight loss last on Mounjaro?
Weight loss continues as long as you remain on Mounjaro and maintain a reduced-calorie diet and physical activity. Most clinical trial participants lost weight over 72 weeks. Long-term outcomes depend on ongoing lifestyle management and whether you continue the medication.
Can I lose weight without being on the highest Mounjaro dose?
Yes. Clinical trials showed meaningful weight loss at all doses — 5 mg, 10 mg, and 15 mg. Not everyone needs the maximum dose. Your prescriber will assess the right dose for you based on your health, tolerance, and results.
What if I reach my goal weight — do I stop Mounjaro?
That is a decision to make with your prescriber. Some people continue Mounjaro to maintain weight loss, while others stop once their goal is reached. Stopping may result in some weight regain, so your prescriber will advise on the best approach for your individual situation.
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.