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
Heart Rate and Weight Loss — What You Need to Know
Heart rate changes during weight loss and exercise, and understanding this connection is important for your health. If you're looking to lose weight in the UK, there are several evidence-based approaches available — from lifestyle changes to prescription medications. The NHS recognises weight management as an important health goal, and GLP-1 medications like Mounjaro and Wegovy offer clinically proven support for eligible adults. This guide explains your options and how to find out if prescription weight loss medication might be right for you.
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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 and Eligibility
Three prescription weight loss medications are currently licensed in the UK:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 injection, taken once weekly. In clinical trials, participants lost an average of 15–21% of their body weight when combined with diet and exercise.
- Wegovy (semaglutide) — a GLP-1 injection, taken once weekly. Clinical trials showed average weight loss of approximately 15% of body weight.
- Saxenda (liraglutide) — a GLP-1 injection, taken once daily.
You may be eligible for weight loss medication if you have a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply. Use our free BMI calculator to check your current BMI — this is the first step in understanding your eligibility.
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 vs Private Prescribing — How to Get Started
NHS access: Referral to a tier 3 specialist weight management service through your GP. Availability varies by region and waiting times can be lengthy in many areas.
Private access: Online consultation with a UK-licensed prescriber, followed by prescription from a GPhC-registered pharmacy. Available without NHS referral and typically faster access than NHS services.
Start by speaking to your GP about your weight management goals. They can assess your health, discuss whether prescription medication is appropriate for you, and either refer you to NHS services or advise you on private options. Track your progress using our free progress tracker as you work towards your weight management goals.
- 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 heart rate changes affect weight loss?
Yes. During weight loss and exercise, your heart rate increases to deliver more oxygen to muscles. A healthy heart rate during moderate exercise is 50–70% of your maximum heart rate. Regular physical activity strengthens your cardiovascular system and supports sustainable weight loss. Always consult your GP before starting a new exercise programme, especially if you have existing health conditions.
What is the difference between Mounjaro and Wegovy for weight loss?
Both are prescription-only injections taken once weekly. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Mounjaro clinical trials showed slightly higher average weight loss (15–21% vs 15%), but individual results vary significantly. Your prescriber will assess which is more suitable for you based on your health profile. Try our GLP-1 weight loss calculator to estimate potential outcomes.
How do I know if I'm eligible for prescription weight loss medication in the UK?
You're potentially eligible if your BMI is 30 or above, or 27–29.9 with weight-related health conditions like diabetes, high blood pressure, or sleep apnoea. South Asian, Chinese, Black African, and Black Caribbean adults may be eligible at lower BMI thresholds. Use our free BMI calculator to check your current BMI, then speak to your GP about whether prescription medication is appropriate for you.
What is the difference between NHS and private weight loss medication?
NHS access requires referral to a specialist weight management service through your GP, with possible waiting lists. Private access involves online consultation with a UK-licensed prescriber and prescription from a GPhC-registered pharmacy — faster but with costs typically £129–£320 per month. Both routes require a clinical assessment. Your GP can discuss which option is best for your situation.
Can weight loss medication replace diet and exercise?
No. Prescription weight loss medications like Mounjaro and Wegovy are designed to support a reduced-calorie diet and increased physical activity — not replace them. Clinical trials that showed weight loss benefits included participants following structured diet and exercise plans. Sustainable weight loss requires ongoing lifestyle changes. Your prescriber will discuss realistic expectations and long-term weight management strategies.
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.