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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How To Break A Weight Loss Plateau On Mounjaro
Weight loss plateaus are common on Mounjaro, even when the weekly weight loss injection is working well initially. A plateau typically occurs after 3–6 months when your body adapts to the medication and reduced calorie intake. The good news is there are evidence-based strategies to restart progress, from dose adjustments to lifestyle changes. Understanding how Mounjaro works—and how it compares to alternatives like Wegovy—can help your prescriber find the right approach for you. This guide covers practical steps to break through and keep moving forward.
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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.
Understanding Plateaus: Mounjaro vs Wegovy Mechanism
A weight loss plateau happens when your body reaches a new equilibrium despite continued calorie deficit, often 3–6 months into treatment. Mounjaro (tirzepatide) uses a dual GIP and GLP-1 mechanism—activating two hormone pathways—which clinical trials (SURMOUNT-1) showed produced average weight loss of approximately 20% body weight. Wegovy (semaglutide) works through GLP-1 alone, with STEP trial data showing approximately 15% average weight loss.
The dual mechanism can sometimes lead to faster initial results with Mounjaro, but both medications work similarly to reduce appetite and slow gastric emptying. Once your body adapts, progress naturally slows. This is not a failure of the medication—it reflects metabolic adaptation. A plateau doesn't mean Mounjaro isn't working; it means your body has adjusted to the new calorie intake and medication dose. Your prescriber may recommend dose titration (increasing from your current Mounjaro KwikPen strength) or lifestyle adjustments to restart progress.
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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
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Practical Strategies To Break Through A Plateau
1. Review calorie intake: Use a food diary or app for one week to check whether calories have crept back up—portion sizes often increase unconsciously over months. A 500 kcal/day deficit typically supports ~0.5 kg weekly loss; below that, progress slows.
2. Increase physical activity: Add 150 minutes of moderate aerobic activity weekly (brisk walking, cycling) or strength training 2–3 times weekly. Muscle loss during weight loss reduces metabolism; resistance training preserves muscle mass.
3. Discuss dose adjustment with your prescriber: If you're below the maximum dose of 15 mg weekly, increasing your Mounjaro dose may restart progress—this requires clinical review.
4. Track progress beyond the scale: Use our free progress tracker to log measurements, energy levels, and clothing fit—weight loss often pauses while body composition improves.
- 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.
How long does a plateau last on Mounjaro?
Plateaus typically last 4–8 weeks. Weight loss often resumes with dose adjustment, lifestyle changes, or simply continued adherence. If no progress after 8 weeks despite maximum effort, discuss alternative strategies with your prescriber.
Should I switch from Mounjaro to Wegovy if I hit a plateau?
Not necessarily. Switching medications is a prescriber decision based on individual response. Wegovy is a single GLP-1 agonist (not dual mechanism), but both medications cause plateaus at similar timeframes. Dose adjustment on Mounjaro is often tried first.
Can I take a higher dose of Mounjaro to break a plateau?
Only under prescriber guidance. Mounjaro titrates from 2.5 mg up to maximum 15 mg weekly. If you're below 15 mg, your prescriber may recommend dose increase. This requires clinical assessment—higher doses aren't suitable for everyone.
Does a plateau mean Mounjaro has stopped working?
No. A plateau reflects metabolic adaptation, not medication failure. Your body has adjusted to reduced calories and the medication effect. Progress can restart with calorie review, activity increase, or dose adjustment—all evidence-based strategies.
Can I use the NHS BMI calculator to track plateau progress?
Yes—recalculate your BMI regularly using our free BMI calculator to monitor whether body composition is improving even if weight is stable. Also use our progress tracker to log measurements, energy, and how clothes fit for a fuller picture.
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.