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
What Happens at Mounjaro Week 6?
At week 6 of Mounjaro treatment, you'll be moving from your starting 2.5 mg dose to the first maintenance dose of 5 mg. This is a critical point in your treatment journey — your body is adapting to the medication, and your prescriber will assess how you've tolerated the initial dose before escalating. Most people experience noticeable changes to appetite and eating patterns by this stage. Understanding what to expect at week 6 helps you stay informed and manage any side effects confidently as your treatment progresses.
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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 at Week 6
Mounjaro follows a structured dose titration schedule designed to help your body adjust gradually. At week 6, you move from the 2.5 mg starting dose to 5 mg — the first proper maintenance dose. This escalation is standard for all patients unless your GP or prescriber advises otherwise due to side effects.
- Week 1–4: 2.5 mg (starting dose)
- Week 5–8: 5 mg (first escalation)
- Week 9–12: 7.5 mg (optional further increase)
- Weeks 13+: Further escalation up to maximum 15 mg
Each dose is a once-weekly injection via the KwikPen. At week 6, you'll be administering your second 5 mg dose. Clinical trials showed that participants on 5 mg experienced average weight loss of around 15% over the treatment period, though individual results vary significantly. Your prescriber may slow or pause escalation if you're experiencing significant side effects.
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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.
Side Effects and Tolerance at Week 6
By week 6, most people have experienced some side effects from the initial 2.5 mg dose — commonly nausea, diarrhoea, or reduced appetite. The good news is that most gastrointestinal side effects tend to improve over weeks 2–4 as your body adapts. Some people find that starting the 5 mg dose brings a temporary return of mild nausea, but this usually settles within a few days.
Common experiences at week 6 include: clearer appetite signals, reduced food cravings, feeling full on smaller portions, and improved energy levels as nausea subsides. If you're experiencing severe or persistent side effects — such as vomiting, severe constipation, or stomach pain — contact your GP or prescriber immediately. Never stop or adjust your dose without medical guidance. Track your symptoms using our free progress tracker to share with your healthcare team.
- 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.
Will I lose weight by week 6 of Mounjaro?
Weight loss varies significantly between individuals. Most people notice appetite suppression and reduced food cravings by week 6, but measurable weight loss (0.5–1 kg per week) typically becomes more consistent weeks 8–12. Your BMI calculator can help you track baseline BMI before starting treatment. Clinical trials showed average weight loss of 15% over the full treatment course — patience is key during the first month.
Should I move to 5 mg at week 6 if side effects are bad?
Always discuss side effects with your prescriber before week 6. If you're experiencing significant nausea, vomiting, or other concerns, your GP may recommend staying on 2.5 mg longer or escalating more slowly. Never adjust your dose independently — your prescriber can guide the best approach for your individual tolerance.
What's the difference between Mounjaro and Wegovy at week 6?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro's dual mechanism may lead to slightly greater appetite suppression, and the titration schedule differs — Mounjaro escalates faster (2.5 mg to 5 mg by week 5, versus semaglutide's 0.25 mg to 0.5 mg at week 5). Individual responses vary, and only your prescriber can advise which is suitable for you.
Do I need a UK prescription to get Mounjaro at week 6?
Yes, Mounjaro is prescription-only in the UK. You'll receive a prescription from your GP or a UK-licensed prescriber following a clinical assessment. Access is available through NHS specialist tier 3 weight management services (though availability varies by region and waiting lists can be long) or through private GPhC-registered online prescribing. Your prescriber must reassess your suitability before each dose escalation.
How do I manage side effects while escalating to 5 mg?
Stay hydrated, eat small frequent meals, and avoid fatty or spicy foods if experiencing nausea. Ginger tea, anti-nausea medications (discuss with your GP), and slow eating can help. Most side effects improve by weeks 8–10. Keep a log of symptoms using our free progress tracker — this helps your prescriber understand your tolerance and adjust your plan if needed. Contact your GP if side effects are severe or persistent.
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.