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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How Often Do You Take A Maintenance Dose Of Mounjaro?
Mounjaro (tirzepatide) is a once-weekly prescription-only injection for weight management in UK adults. The maintenance dose is taken exactly once every seven days, after a titration period where your dose gradually increases. Most people reach their maintenance dose between weeks 17 and 20, depending on tolerability. Once you've found the right dose for you, you'll continue taking one injection every week as part of your ongoing weight management plan. Your prescriber will monitor your progress and adjust if needed.
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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 Schedule And Titration Timeline
Mounjaro follows a four-week titration schedule, meaning you spend at least four weeks on each dose before increasing. The full titration pathway is: 2.5 mg (weeks 1–4), 5 mg (weeks 5–8), 7.5 mg (weeks 9–12), 10 mg (weeks 13–16), 12.5 mg (weeks 17–20), and finally 15 mg (week 21 onwards) as the maximum dose. Most people reach their maintenance dose — the dose that works best for them — somewhere between 5 mg and 15 mg once weekly.
- Starting dose: 2.5 mg once weekly for 4 weeks
- Maintenance range: Usually 5 mg to 15 mg once weekly
- Time to maintenance: Typically 17–20 weeks, but some people stabilise at lower doses
- Ongoing schedule: One injection every seven days indefinitely
Each Mounjaro KwikPen contains four weekly doses, so you'll need a new pen every four weeks. Your prescriber will assess whether you need to increase your dose based on your weight loss progress and how well you tolerate the medication. Not everyone reaches the maximum 15 mg dose — your individual maintenance dose depends on your response and any 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.
What Happens Once You Reach Maintenance?
Once you've reached your maintenance dose — the dose you'll stay on long-term — your routine becomes straightforward: one injection once per week, on the same day each week. You'll continue this schedule as long as you're taking Mounjaro for weight management. Your GP or prescriber will arrange regular check-ins to monitor your weight loss progress, any side effects, and your overall health. If you experience side effects or your weight loss plateaus, your prescriber may adjust your dose up or down.
Try our GLP-1 weight loss calculator to project how Mounjaro might support your weight management goals at different doses. Remember that medication works best alongside a reduced-calorie diet and increased physical activity — Mounjaro is a tool to support these lifestyle changes, not a replacement for them.
- 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 Mounjaro truly once weekly?
Yes, Mounjaro is a once-weekly injection. Each dose is given exactly seven days apart. Each KwikPen contains four pre-filled doses for four weeks of treatment. You inject the same time each week for consistency.
What if I miss a Mounjaro dose?
If you miss a dose, take it within four days of when it was due, then continue your normal weekly schedule. If more than four days have passed, skip that dose and take your next injection on your normal scheduled day. Never double up.
How long do you stay on Mounjaro maintenance?
You stay on your maintenance dose as long as it's helping with weight management and your prescriber believes it's appropriate. There's no set time limit. Regular check-ups with your GP or prescriber will determine if ongoing treatment remains right for you.
Can your Mounjaro maintenance dose change?
Yes, your prescriber may adjust your maintenance dose based on your results and tolerance. Some people move up if they're tolerating it well; others may step down if side effects are troublesome. Adjustments are individualised.
What's the difference between tirzepatide and other weight loss injections?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1-only medication. Both are once-weekly injections licensed in the UK. Clinical trials showed different weight loss profiles, but individual results vary significantly.
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.