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 to Get the Best Results From Mounjaro
Getting the best results from Mounjaro involves more than just the injection itself. While tirzepatide (Mounjaro's active ingredient) is effective as a dual GLP-1 and GIP receptor agonist, achieving meaningful weight loss depends on combining prescription treatment with lifestyle changes, proper dose titration, and realistic expectations. This guide covers how to optimise your Mounjaro use in the UK, whether you're accessing it through the NHS or privately, and what evidence tells us about maximising outcomes.
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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.
Optimising Mounjaro: Dose, Diet, and Lifestyle
Proper dose titration is essential. Mounjaro starts at 2.5 mg weekly and increases gradually — most people reach 5 mg, 10 mg, or 15 mg depending on tolerance and response. Rushing doses or skipping the adjustment phase reduces effectiveness and increases side effects like nausea. Stay on each dose for at least 4 weeks before increasing.
Diet and exercise are non-negotiable. Clinical trials showed Mounjaro helped participants lose an average of 15–21% of body weight, but only when combined with a reduced-calorie diet and increased physical activity. The medication reduces appetite and food cravings, but it cannot work alone. Aim for a sustainable calorie deficit of around 500 kcal per day.
- Track your intake using food diaries or apps
- Increase protein intake to preserve muscle during weight loss
- Aim for 150 minutes of moderate physical activity weekly
- Stay hydrated — sometimes thirst mimics hunger
Consistency matters more than perfection. Small, sustainable changes outperform extreme restrictions that cannot be maintained.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Accessing Mounjaro in the UK: NHS vs Private Routes
NHS access: Mounjaro is now available through NICE-approved specialist weight management services (tier 3/4). Your GP can refer you, but availability varies significantly by region and waiting lists can be lengthy — sometimes months or years. NHS prescriptions are significantly cheaper for eligible patients.
Private access: You can obtain a UK prescription through an online clinical assessment with a licensed prescriber, without NHS referral. This route is faster — typically assessed and prescribed within days — but costs range from approximately £130–£300+ monthly depending on dose. Costs increase as you titrate to higher doses. Payment is per prescription, and you'll need ongoing prescriptions as you progress through doses.
Both routes require a prescriber to assess your eligibility based on BMI (usually 30+) and any weight-related health conditions. Use our free GLP-1 weight loss calculator to explore projected outcomes at different doses before committing.
What to expect from the online assessment process: Private consultations typically ask about your medical history, current medications, weight, height, and why you're seeking treatment. The prescriber (a doctor or nurse prescriber) will determine suitability, discuss side effects and expectations, and issue a prescription if appropriate. Your prescriptions are dispensed by a registered UK pharmacy. You'll need to self-inject weekly using the Mounjaro KwikPen device — training is provided. Track your progress with our free progress tracker to monitor weight loss alongside lifestyle changes, and use our BMI calculator regularly to see how your BMI category changes as you lose weight.
- 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.
Does Mounjaro alone cause weight loss without diet and exercise?
No. Clinical trials combined Mounjaro with reduced-calorie diet and increased physical activity. The medication reduces appetite and cravings, making it easier to stick to healthy changes, but it is not a standalone solution. Results vary significantly based on lifestyle adherence.
How much does Mounjaro cost privately in the UK?
Costs typically range from £130–£300+ per month depending on dose and provider. Starting doses (2.5–5 mg) cost less than higher doses (10–15 mg). Prices vary between online prescribing services, so it's worth comparing. NHS prescription costs are significantly lower for eligible patients.
What is the difference between Mounjaro and Wegovy for weight loss?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) activates GLP-1 only. Clinical trials show Mounjaro may achieve slightly greater average weight loss (~20.9% vs ~14.9%), but both are effective. Individual results vary. Both are prescription-only and require clinical assessment.
How long does it take to see results from Mounjaro?
Most people notice reduced appetite within days, but significant weight loss takes 8–12 weeks. Clinical trials measured results at 72 weeks. Patience is essential — sustainable weight loss happens gradually at 0.5–1 kg per week. Dose titration also means results build over several months as you reach your effective dose.
Can I switch from Mounjaro to Wegovy or other weight loss injections?
Potentially, yes, but any change must be managed by your prescriber. There is no official conversion chart between medications. Your prescriber will assess whether a switch is appropriate based on your response, tolerance, and health status. Never stop or switch medications without professional guidance.
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.