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
Do You Need To Exercise On Mounjaro?
Exercise isn't strictly required to take Mounjaro (tirzepatide), but it significantly improves your results. Mounjaro works best when combined with reduced-calorie diet and regular physical activity — this combination is what clinical trials used to achieve weight loss. While the injection alone may help reduce appetite, sustainable weight management typically requires lifestyle changes alongside medication. Your GP or prescriber will discuss the best approach for your individual circumstances.
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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 Exercise Works With Mounjaro Treatment
Clinical trials that demonstrated Mounjaro's effectiveness in the SURMOUNT studies combined the tirzepatide injection with dietary changes and physical activity. This combination produced the best results — not medication alone.
When you take Mounjaro, the injection helps regulate appetite by activating GIP and GLP-1 hormone pathways, making it easier to eat less and feel fuller after smaller meals. However, adding exercise amplifies these benefits by:
- Preserving muscle mass during weight loss (medication alone can increase muscle loss)
- Improving cardiovascular health and blood pressure
- Boosting metabolic rate and energy levels
- Enhancing mental health and mood
- Reducing risk of type 2 diabetes and heart disease
- Supporting long-term weight maintenance after stopping the injection
NHS guidance emphasises that weight loss medication works best alongside lifestyle modifications, not as a replacement for them. Even moderate physical activity — such as 150 minutes of brisk walking per week — significantly improves health outcomes when combined with Mounjaro.
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.
NHS Access And UK Prescription Costs For Mounjaro
NHS route: Mounjaro is available through NHS specialist tier 3/4 weight management services, but availability varies significantly by region. You'll need a referral from your GP and may face waiting lists of several months. Cost is covered by the NHS where prescribed.
Private route: Mounjaro is available through GPhC-registered online pharmacies following a clinical assessment. Private costs typically range from £129–£320 per month depending on your dose. Starting doses (2.5–5mg) are generally less expensive than higher maintenance doses (10–15mg). Private prescriptions are issued by UK-licensed prescribers and dispensed by regulated pharmacies.
Both routes require a clinical assessment to confirm eligibility. Use our free GLP-1 weight loss calculator to estimate potential results at different doses, and our BMI calculator to check your starting point before discussing options with your GP or a prescriber.
- 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.
Can I lose weight on Mounjaro without exercising?
Mounjaro may help reduce appetite and support some weight loss without exercise, but results are significantly better when combined with physical activity and a reduced-calorie diet. Clinical trials achieved their results using all three elements together. Exercise also helps preserve muscle mass and supports long-term weight maintenance.
What type of exercise works best with Mounjaro?
The NHS recommends 150 minutes of moderate-intensity aerobic activity (like brisk walking) per week, plus muscle-strengthening exercises twice weekly. Any regular physical activity helps — walking, swimming, cycling, or gym work all provide benefits. Start gently and gradually increase intensity, especially if you're new to exercise.
How much weight can I lose on Mounjaro with exercise?
Clinical trial averages showed 15–clinically studied weight loss at maximum doses over 72 weeks, combined with diet and exercise. Individual results vary considerably. Using our GLP-1 weight loss calculator can help estimate potential outcomes based on your starting weight and dose, but your GP can provide personalised guidance.
What's the difference between NHS and private Mounjaro in the UK?
NHS Mounjaro is free but available through specialist services with potential waiting lists and regional variation. Private Mounjaro (tirzepatide) is available via online prescribers at approximately £129–£320 per month depending on dose. Both require clinical assessment and prescription — neither is available without a prescriber's approval.
Do I need to be eligible for NHS Mounjaro to get a private prescription?
No. Private prescribers assess eligibility independently based on your BMI and health status. You don't need an NHS referral or specialist service access. However, you must meet the prescriber's clinical criteria (typically BMI 30+ or BMI 27+ with weight-related health conditions) and undergo an online clinical assessment.
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.