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
Running and Weight Loss: When Medication Can Help
Running is an excellent way to support weight loss and improve cardiovascular health, but for many UK adults, exercise alone isn't enough. If you're struggling to lose weight despite regular running and healthy eating, prescription weight management medication may be an option worth discussing with your GP. The UK now offers several evidence-based treatments that can work alongside your running routine and dietary changes to help you achieve sustainable results.
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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.
UK-Licensed Weight Loss Medications Available Now
Three prescription medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are all GLP-1 or dual GIP/GLP-1 receptor agonists—medications that help regulate appetite and support feeling fuller after smaller meals. In clinical trials, Mounjaro helped participants lose an average of 15–21% of their body weight, whilst Wegovy showed average weight loss of around 15% over 68 weeks. Individual results vary significantly.
- Mounjaro: Once-weekly injection, doses from 2.5mg to 15mg, typically used for adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions
- Wegovy: Once-weekly injection, maximum dose 2.4mg, with similar eligibility criteria to Mounjaro
- Saxenda: Daily injection, up to 3mg per day, an alternative for those who prefer daily dosing
These medications are prescription-only and require a clinical assessment to determine suitability. They are most effective when combined with regular physical activity—like running—and a reduced-calorie diet.
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 Versus Private Prescription in the UK
In the UK, prescription weight loss medications are available through two routes. NHS access is through specialist tier 3 weight management services, typically accessed via GP referral, though availability and waiting times vary significantly by region. Private prescription is available through GPhC-registered online pharmacies following a clinical assessment by a UK-licensed prescriber, without needing an NHS referral.
To find out if you're eligible, discuss your weight management goals with your GP. They'll assess your BMI, any weight-related health conditions (such as type 2 diabetes, high blood pressure, or sleep apnoea), and whether medication is appropriate for you. Use our free BMI calculator to check your starting point, and our GLP-1 weight loss calculator to explore potential outcomes at different doses alongside your running and lifestyle changes.
- 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 take weight loss medication if I run regularly?
Yes. In fact, prescription weight loss medications like Mounjaro and Wegovy are most effective when combined with regular physical activity and a healthy diet. Running or other regular exercise supports better weight loss results and improves overall cardiovascular health. Always inform your prescriber about your current activity level during clinical assessment.
Will weight loss medication affect my running performance?
Most runners tolerate these medications well. Common side effects like nausea typically improve after a few weeks as your body adjusts. Some people report feeling lighter and more energised with weight loss. If you experience dizziness or unusual fatigue, discuss this with your GP or prescriber—dose adjustments may help.
Do I need to change my diet if I take weight loss medication?
Yes. Weight loss medications work best alongside a reduced-calorie diet and regular exercise. They help reduce appetite and cravings, making it easier to stick to healthier eating habits. Your prescriber or a registered dietitian can provide personalised guidance on nutrition alongside your running routine.
How do I know if I'm eligible for prescription weight loss medication on the NHS?
NHS eligibility generally requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions like diabetes or high blood pressure. Check your BMI using our free calculator, then discuss eligibility with your GP. They can refer you to specialist weight management services if appropriate. Access varies by region.
How long do I need to take weight loss medication?
Treatment duration varies by individual. Some people take it for several months to reach their goal weight, then stop. Others continue longer-term to maintain results. Your prescriber will monitor your progress and discuss the best approach for you. Sustainable results typically require ongoing lifestyle changes, including continued running and healthy eating habits.
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.