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 Electrolytes Help With Weight Loss?
Electrolytes (sodium, potassium, magnesium) are essential minerals that regulate hydration and muscle function, but they do not directly cause weight loss. While staying properly hydrated is important during any weight management programme, electrolyte supplements alone won't reduce body fat. If you're exploring weight loss options in the UK, prescription weight management medications like Mounjaro and Wegovy have strong clinical evidence behind them. Understanding what actually works—and what doesn't—is crucial when planning your weight management journey.
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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.
Prescription Weight Loss Options in the UK
If you're interested in weight management beyond basic nutrition, the NHS and private prescribers in the UK now offer evidence-based prescription medications specifically approved for weight loss. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist injection that, in clinical trials, helped participants lose an average of 15–21% of their body weight over 72 weeks. Wegovy (semaglutide) is a GLP-1 injection that supported an average weight loss of approximately 15% of body weight in clinical trials.
Both are prescribed once weekly and work by reducing appetite, helping you feel fuller after smaller meals, and supporting more sustainable dietary changes. Saxenda (liraglutide) is another NHS-licensed option, though it requires daily injections rather than weekly.
These medications are prescription-only and eligibility is assessed individually by a licensed prescriber based on your BMI, health conditions, and medical history. Calculate your BMI now using our free BMI calculator above to see if you may meet initial eligibility criteria.
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 vs Private Access and Next Steps
Access to prescription weight loss medication in the UK differs between NHS and private routes. NHS access is through specialist tier 3 weight management services, typically requiring a GP referral. Availability and waiting times vary significantly by region. Private access is available through GPhC-registered online prescribers following a clinical assessment, without needing an NHS referral.
Whichever route you choose, weight loss medications work alongside—not instead of—dietary changes and increased physical activity. Our free GLP-1 weight loss calculator can help you estimate potential weight loss outcomes at different doses. Speak to your GP first to discuss which option is suitable for you and your health profile.
- 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.
Do electrolytes actually help with weight loss?
Electrolytes (sodium, potassium, magnesium) are vital for hydration and muscle function, but they don't directly cause weight loss. Staying hydrated supports overall health and can help you feel fuller, which may help during a weight loss programme, but electrolyte supplements alone won't reduce body fat or weight.
What prescription weight loss medications are available in the UK?
Three medications are NHS-licensed for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All are prescription-only. Clinical trials showed Mounjaro and Wegovy helped participants lose 15–21% and approximately 15% of body weight respectively, alongside diet and exercise changes.
Who is eligible for prescription weight loss medication on the NHS?
Eligibility typically requires a BMI of 30 or above, or 27 or above with weight-related health conditions (such as type 2 diabetes, high blood pressure, or cardiovascular disease). Some individuals of South Asian, Chinese, or Black African heritage may have lower BMI thresholds. Your GP can assess your eligibility.
Can I access weight loss injections privately without an NHS referral?
Yes. Private GPhC-registered online prescribers can issue prescriptions following a clinical assessment, without requiring an NHS referral. Private costs vary by dose and provider, typically ranging from £129–£320 monthly. Always ensure the prescriber is UK-licensed and the pharmacy is GPhC-registered.
Do weight loss medications work without diet and exercise changes?
No. Prescription weight loss medications like Mounjaro and Wegovy work best alongside reduced-calorie diet and increased physical activity. They reduce appetite and help you feel fuller, but sustainable weight loss requires commitment to lifestyle changes as well.
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.