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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Is 2.5 Mg Mounjaro Enough for Weight Loss?
The 2.5 mg dose is the starting dose of Mounjaro (tirzepatide) in the UK and is not typically considered a full treatment dose — most people will need to escalate to higher doses for meaningful weight loss results. The dose titration schedule means you spend the first four weeks on 2.5 mg before progressing to 5 mg, then potentially higher. This gradual approach allows your body to adjust and helps minimise side effects. Whether 2.5 mg is "enough" depends on your individual response, weight, and health goals. Your prescriber will guide you through dose escalation based on your progress and tolerance.
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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 Mounjaro Dose Escalation Works
Mounjaro follows a structured dose escalation schedule in the UK. You start at 2.5 mg once weekly for 4 weeks, then progress to 5 mg for the next 4 weeks minimum. If needed, the dose can increase further to 7.5 mg, 10 mg, 12.5 mg, and finally the maximum of 15 mg once weekly. Each dose step takes at least 4 weeks before escalation. The 2.5 mg starting dose serves two purposes: it allows your body to adjust to the dual GIP and GLP-1 mechanism of tirzepatide, and it helps your prescriber assess your tolerance before moving to higher doses. Most people remain on 2.5 mg for only the first month unless side effects are severe. Clinical trial data showed that meaningful weight loss typically occurs at doses of 5 mg and above, with average weight loss increasing at higher doses.
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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.
Will You Stay on 2.5 Mg Mounjaro?
It is very unlikely you will remain on the 2.5 mg dose long-term. This dose is designed as a transition step, not a maintenance dose. Your prescriber will review your progress and side effects after four weeks, then move you to 5 mg. If you experience severe nausea or other side effects at 2.5 mg, your prescriber may keep you on this dose for longer or adjust the schedule, but this is uncommon. The goal is to reach a dose where you see weight loss benefits while managing side effects effectively. Some people find their optimal dose at 5 mg, while others benefit from higher doses up to 15 mg. You can track your progress using our free GLP-1 weight loss calculator to see projected outcomes at different doses based on clinical trial data. Your prescriber will personalise your escalation schedule based on your individual response and health needs.
- 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.
Can I stay on 2.5 mg Mounjaro if it's working?
If you're experiencing genuine weight loss at 2.5 mg, your prescriber may discuss continuing or escalating. However, 2.5 mg is designed as a starting dose. Higher doses typically deliver greater weight loss. Your prescriber will assess whether staying on 2.5 mg meets your health goals or if escalation would be beneficial.
What's the difference between Mounjaro and Wegovy starting doses?
Mounjaro starts at 2.5 mg (tirzepatide), while Wegovy starts at 0.25 mg (semaglutide). Despite lower absolute numbers, Wegovy's 0.25 mg and Mounjaro's 2.5 mg are roughly equivalent in potency. Mounjaro is a dual GIP and GLP-1 agonist; Wegovy targets GLP-1 only.
How long before I notice weight loss on 2.5 mg Mounjaro?
Weight loss typically takes 4–8 weeks to become noticeable, even at higher doses. The first 4 weeks on 2.5 mg is an adjustment phase. Most people see more significant results once they escalate to 5 mg and beyond. Individual timelines vary considerably.
What if I have severe side effects on 2.5 mg Mounjaro?
Report side effects to your prescriber immediately. They may extend your time on 2.5 mg, slow escalation, or adjust your injection technique. Severe side effects can indicate the dose needs adjustment. Never stop without guidance from your prescriber.
Is 2.5 mg Mounjaro a full prescription dose?
No. The 2.5 mg dose is the starting dose only, designed for dose escalation. It's not a maintenance or therapeutic dose. A standard maintenance dose is typically 5 mg or higher, depending on your clinical response and prescriber assessment.
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.