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 Should You Increase Your Mounjaro Dose?
Your Mounjaro dosage isn't increased automatically — dose escalation follows a specific schedule based on your response and how well you tolerate each level. In the UK, Mounjaro (tirzepatide) typically starts at 2.5 mg and increases gradually over weeks, with a minimum of 4 weeks at each dose before stepping up. Your prescriber will assess your progress, side effects, and individual health situation to decide whether you're ready to escalate. Understanding this timeline helps you know what to expect as you begin your weight management journey.
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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.
Mounjaro Dose Escalation Schedule
The standard Mounjaro dose escalation follows this timeline for most UK patients:
- Weeks 1–4: 2.5 mg once weekly (starting dose)
- Weeks 5–8: 5 mg once weekly (first escalation)
- Weeks 9–12: 7.5 mg once weekly (optional second escalation)
- Weeks 13–16: 10 mg once weekly (optional third escalation)
- Weeks 17–20: 12.5 mg once weekly (optional fourth escalation)
- Week 21+: 15 mg once weekly (maximum dose)
Crucially, you must spend at least 4 weeks on each dose before your prescriber can increase it. This minimum gap is essential — it allows your body to adjust and ensures your prescriber can accurately assess how well the current dose is working. Your KwikPen will contain four weeks of injections at each dose level.
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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.
Factors That Influence Dose Progression
Not everyone escalates through the full dose range. Your prescriber will consider several factors when deciding whether to increase your Mounjaro dose: your weight loss progress (whether you're losing weight consistently), how well you're tolerating the current dose, any side effects you're experiencing, and your individual health goals. If you're losing weight steadily and side effects are manageable, progression to the next dose typically follows the standard 4-week schedule. However, if you're experiencing persistent nausea, vomiting, or other side effects, your prescriber may extend the time at your current dose or recommend staying at a lower maintenance level. Your GP or prescriber will discuss this with you at your regular check-ins — this is a personalised decision based on your individual response.
- 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.
Do I have to increase my Mounjaro dose every 4 weeks?
No. The 4-week minimum is the earliest you can escalate, but your prescriber may recommend staying at your current dose if you're achieving good weight loss results and tolerating it well. Many patients find their ideal dose somewhere between 5 mg and 10 mg and remain on that dose long-term rather than reaching the maximum 15 mg.
What happens if I experience side effects during dose escalation?
Tell your prescriber immediately. Common side effects like nausea often ease over time, but if they're severe or persistent, your prescriber may slow your escalation or keep you at your current dose longer. You can also use our free GLP-1 weight loss calculator to see projected outcomes at different dose levels while you decide with your prescriber.
Can my dose be decreased if I'm having problems?
Yes. If side effects become difficult to manage, your prescriber may recommend staying at your current dose or even temporarily reducing it. This is a safe, personalised decision made during your regular clinical check-ins. Never stop or reduce your dose without consulting your prescriber.
What's the maximum Mounjaro dose I can take?
The maximum licensed dose of Mounjaro (tirzepatide) in the UK is 15 mg once weekly. Your prescriber will recommend the most effective dose for your individual needs — this may be anywhere from 5 mg to 15 mg, depending on your weight loss progress and tolerability.
How often should I check in with my prescriber about dose increases?
If you're accessing Mounjaro privately, your prescriber will typically review your progress at regular intervals (often every 4 weeks initially). On the NHS, review frequency varies by your specialist weight management service. Use our free BMI calculator and progress tracker to monitor your own weight changes between appointments, which helps you and your prescriber make informed decisions together.
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.