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
Can I Stay On 2.5 Mounjaro Permanently?
Yes, you can stay on the 2.5 mg Mounjaro dose if your prescriber agrees it's effective for you, though this is uncommon in clinical practice. The 2.5 mg dose is designed as a starting dose for the first four weeks to allow your body to adjust, before gradually increasing. However, some people may find this dose sufficient for their weight management goals alongside diet and exercise changes. Your GP or prescriber will assess whether staying on 2.5 mg is appropriate based on your individual health, weight loss progress, and tolerance of the medication. Use our free GLP-1 weight loss calculator to explore potential outcomes at different Mounjaro doses.
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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 Titration Works in the UK
Mounjaro (tirzepatide) follows a structured dose titration schedule where you increase the dose gradually every 4 weeks rather than staying on one dose permanently. This approach helps your body adjust to the medication and allows your prescriber to find your optimal therapeutic dose. The standard progression is: 2.5 mg (weeks 1–4), 5 mg (weeks 5–8), 7.5 mg (weeks 9–12), and continuing up to the maximum 15 mg dose. The 2.5 mg starting dose is intentionally low to minimise initial side effects like nausea and stomach upset. Most people progress beyond 2.5 mg because higher doses in clinical trials showed greater average weight loss — around 15–21% body weight depending on the final dose. However, if you experience significant side effects or achieve meaningful weight loss at 2.5 mg, your prescriber may recommend staying on this dose longer or indefinitely, though this is not standard practice.
Clinically BackedWeight Loss
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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.
When Your Prescriber Might Keep You on 2.5 Mounjaro
Your prescriber may recommend staying on 2.5 mg Mounjaro if: you've achieved substantial weight loss and are reaching your personal goal weight; you're experiencing unmanageable side effects at higher doses; your BMI or health conditions have improved sufficiently; or you're maintaining stable weight loss long-term on this dose. Every person responds differently to tirzepatide, so individual tolerance and effectiveness matter more than following a standard escalation schedule. If you're considering staying on 2.5 mg, discuss this openly with your prescriber before your next dose adjustment. They can review your progress using our BMI calculator to assess your current health metrics and confirm whether continuing 2.5 mg aligns with your treatment goals. Regular monitoring ensures you're receiving the most appropriate dose for your situation.
- 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 2.5 mg Mounjaro enough for weight loss?
The 2.5 mg starting dose is designed for tolerance, not as a therapeutic dose. In clinical trials, people typically needed higher doses (5 mg and above) for meaningful weight loss. However, some people may see modest weight loss on 2.5 mg, especially alongside reduced-calorie diet and increased physical activity. Your prescriber will monitor your progress and adjust accordingly.
What happens if I don't increase my Mounjaro dose?
If you don't increase beyond 2.5 mg, you may not achieve the full weight loss potential that higher doses could provide. Clinical trial data showed greater average weight loss at 10 mg and 15 mg doses compared to lower doses. Your prescriber may recommend dose increases unless you've reached your goal or experience limiting side effects.
Can I stay on Mounjaro long-term once I reach my target weight?
Yes, many people continue Mounjaro indefinitely after reaching target weight to maintain the loss. Your prescriber will reassess whether you should continue, reduce to a lower maintenance dose, or stop gradually. Weight often returns if you stop GLP-1 medication, so long-term use is common for ongoing weight management.
What's the difference between Mounjaro and Wegovy for staying on a low dose?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Both follow dose titration schedules. The main difference is mechanism — Mounjaro's dual action may help some people achieve greater weight loss at lower doses, though both require individual assessment by your prescriber.
How do I know if 2.5 Mounjaro is working for me?
Monitor your weight regularly using our free progress tracker over 4–8 weeks. Look for gradual weight reduction, improved energy, or reduced appetite. Discuss your progress with your prescriber — they'll decide whether to continue 2.5 mg, escalate the dose, or adjust your treatment plan based on your individual response.
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.