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 Is the Best Mounjaro Dose for Weight Loss?
There's no single "best" Mounjaro dose — it varies for each person based on your health, weight, and how well you tolerate the medication. Mounjaro (tirzepatide) is a prescription-only weekly weight loss injection that starts at a low dose and gradually increases over weeks. Your prescriber will find your optimal dose through a structured titration process, balancing weight loss results with side effect management. This guide explains how Mounjaro dosing works in the UK and what to expect.
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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.
How Mounjaro Doses Are Titrated
Mounjaro follows a step-by-step dose titration schedule, increasing every 4 weeks if you tolerate each dose well. You start at 2.5 mg and progress through 5 mg, 7.5 mg, 10 mg, 12.5 mg, and finally to the maximum 15 mg once weekly.
- Weeks 1–4: 2.5 mg (starting dose)
- Weeks 5–8: 5 mg (first maintenance dose)
- Weeks 9–12: 7.5 mg (escalation if tolerated)
- Weeks 13–16: 10 mg (further escalation)
- Weeks 17–20: 12.5 mg (increased dose)
- Week 21+: 15 mg (maximum dose)
Your prescriber may pause at any dose if you're experiencing good weight loss results and managing side effects well. Not everyone reaches 15 mg — many people achieve their weight loss goals at 10 mg or 12.5 mg. The key is finding your personal optimal dose, not necessarily reaching the maximum.
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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.
Expected Weight Loss by Dose
Clinical trial data (SURMOUNT-1) shows that higher doses generally produce greater average weight loss, though results vary significantly between individuals. At 5 mg, participants lost approximately 15% of body weight; at 10 mg, about 19.5%; and at 15 mg, about 20.9% over 72 weeks, alongside reduced-calorie diet and increased physical activity.
However, this doesn't mean you need the highest dose — many people lose substantial weight at lower doses with fewer side effects. Your prescriber will assess your individual response and adjust accordingly. Use our GLP-1 weight loss calculator to estimate potential results based on your current weight and dose, then discuss realistic expectations with your prescriber during your clinical assessment.
Individual factors that influence your optimal dose: your starting weight and BMI, how well you tolerate initial side effects (nausea, diarrhoea), your weight loss progress at each step, any other medications you take, and your underlying health conditions. Some people experience maximum benefit at 10 mg and choose to stay there; others need to progress to 15 mg. Your prescriber will monitor your progress and adjust your titration pace based on your personal response — if side effects are significant, they may slow the increase or keep you at a lower dose longer.
- 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 15 mg Mounjaro always the best dose for weight loss?
No. While 15 mg is the maximum dose, clinical trials show that meaningful weight loss occurs at lower doses too. Many people achieve their weight loss goals at 10 mg or 12.5 mg with fewer side effects. Your prescriber will determine your personal optimal dose based on your progress, tolerability, and individual health factors — not everyone needs or benefits from 15 mg.
How long does it take to reach the maximum Mounjaro dose?
The standard titration schedule takes approximately 20–24 weeks to reach 15 mg, increasing every 4 weeks. However, your prescriber may adjust this timeline if you experience significant side effects or excellent results at a lower dose. Some people remain on lower doses indefinitely.
Can I skip doses or pause my Mounjaro to reduce side effects?
You should never skip doses without guidance from your prescriber. If side effects are severe, contact your healthcare provider — they can adjust your dose, slow your titration, or pause at your current dose. Do not self-adjust; always discuss tolerability concerns with your prescriber.
What dose of Mounjaro is best for someone with a BMI of 30?
There's no fixed dose for a specific BMI. Optimal dosing depends on your individual weight loss progress, side effect tolerance, and prescriber assessment. Use our BMI calculator to understand your starting point, then discuss personalised dosing with your prescriber during your clinical consultation.
Is Mounjaro dose the same as Wegovy dose?
No. Mounjaro and Wegovy (semaglutide) are different medications with different dosing schedules. Mounjaro is a dual GIP/GLP-1 agonist (max 15 mg weekly), while Wegovy is a GLP-1 agonist only (max 2.4 mg weekly). Your prescriber will choose the appropriate medication and dose for your individual needs.
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.