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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Weight Plateau On Mounjaro — What You Need To Know
A weight plateau on Mounjaro is common and doesn't mean the medication has stopped working. Many people experience periods where weight loss slows or temporarily stops, even when taking a weekly weight loss injection like Mounjaro consistently. Understanding why plateaus happen and what your NHS or private prescriber can do about them helps you stay on track with your weight management plan.
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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.
Why Weight Loss Plateaus Happen On Mounjaro
Weight loss plateaus occur when your body adapts to lower calorie intake and reduced appetite from the GIP and GLP-1 receptor agonist effects of Mounjaro. Your metabolic rate may gradually adjust, meaning fewer calories are burned at rest. Additionally, as you lose weight, your daily calorie needs decrease—so the same diet that created a deficit weeks ago may no longer be sufficient.
Other factors contributing to plateaus include:
- Insufficient calorie deficit alongside the medication
- Reduced physical activity or exercise frequency
- Water retention or changes in hormones
- Individual variation in how your body responds to tirzepatide
- Not yet reaching the optimal maintenance dose (Mounjaro titrates from 2.5 mg up to 15 mg)
Plateaus are typically temporary. Many people experience renewed weight loss after weeks or months, particularly if their prescriber adjusts their dose or they recommit to lifestyle changes.
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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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What Your NHS Or Private Prescriber Can Do
If you're on Mounjaro through an NHS specialist tier 3 or 4 weight management service, or through a private prescriber, discuss plateaus at your next review. Your prescriber may increase your Mounjaro dose (minimum 4 weeks between escalations, up to 15 mg maximum), review your dietary intake and activity levels, or adjust other lifestyle factors. They may also check for underlying conditions like thyroid problems affecting metabolism.
Track your progress using a free tool to record both weight changes and how you feel—energy, appetite, clothes fit. Weight loss isn't always linear on the scale, and body composition changes (fat loss vs. muscle) matter more than weekly fluctuations. If you've lost 5–10% of your starting weight, you're already experiencing significant health benefits regardless of plateaus.
If you're on Mounjaro through an NHS specialist tier 3 or 4 weight management service, or through a private prescriber, discuss plateaus at your next review. Your prescriber may increase your Mounjaro dose (minimum 4 weeks between escalations, up to 15 mg maximum), review your dietary intake and activity levels, or adjust other lifestyle factors. They may also check for underlying conditions like thyroid problems affecting metabolism.
Track your progress with our free progress tracker to record both weight changes and how you feel—energy, appetite, clothes fit. Weight loss isn't always linear on the scale, and body composition changes (fat loss vs. muscle) matter more than weekly fluctuations. If you've lost 5–10% of your starting weight, you're already experiencing significant health benefits regardless of plateaus.
- 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 a weight plateau on Mounjaro normal?
Yes, weight plateaus are very common and normal on Mounjaro. They occur because your body adapts to lower calorie intake and reduced appetite. Plateaus don't mean the medication has stopped working—they're a temporary phase that many people move through as they lose weight and their metabolism adjusts.
How long do weight plateaus usually last?
Weight plateaus vary in length—some last 2–4 weeks, others several months. There's no standard timeline. If you remain consistent with diet and activity, weight loss often resumes, especially if your prescriber increases your Mounjaro dose or you optimise other lifestyle factors.
Can my Mounjaro dose be increased if I'm on a plateau?
Yes. Mounjaro starts at 2.5 mg and can be increased every 4 weeks up to 15 mg maximum. If you've reached a plateau, your prescriber may recommend escalating your dose. This decision is individualised and depends on your current dose, side effects, and overall progress.
Should I change my diet if I hit a plateau on Mounjaro?
Consider reviewing your calorie intake and exercise habits. As you lose weight, your daily calorie needs decrease, so a diet that worked weeks ago may need adjustment. Your GP or prescriber can refer you to a dietitian for personalised guidance on maintaining a calorie deficit.
What's the difference between Mounjaro and Wegovy for plateaus?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist; Wegovy (semaglutide) is GLP-1 only. In clinical trials, Mounjaro produced slightly higher average weight loss (~20% vs ~15%), but both medications cause plateaus—weight loss isn't linear on either drug. Your prescriber will recommend based on your individual health.
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.