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
Does Lemon Aid in Weight Loss?
Lemon is often promoted as a weight loss aid, but the evidence for lemon alone is limited. While lemon water may support hydration and digestion, sustainable weight management in the UK typically requires a combination of dietary changes, physical activity, and—for eligible adults—prescription weight loss medications. If you're looking to lose weight, your GP can discuss evidence-based options with you, including NHS weight loss services or prescription medications like Mounjaro and Wegovy.
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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 Available in the UK
For adults struggling with weight management, prescription weight loss medications offer clinically proven support alongside lifestyle changes. The UK has three licensed weight loss injections: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide).
Mounjaro is a once-weekly GIP and GLP-1 receptor agonist that helped participants lose an average of 15–21% of their body weight in clinical trials. Wegovy is a once-weekly GLP-1 injection with average weight loss of around 15% in trials. Both are prescription-only and require clinical assessment before being prescribed.
These medications work by regulating appetite and supporting feeling fuller after meals. They are most effective when combined with reduced-calorie eating and increased physical activity—not as replacements for lifestyle changes. Your GP can assess whether you're eligible based on your BMI and health conditions. Use our GLP-1 weight loss calculator to explore potential outcomes at different doses.
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: How to Get Started
In the UK, prescription weight loss medication is available through two routes: NHS specialist services and private prescribing. NHS access requires referral to a tier 3 or tier 4 weight management service by your GP, though waiting lists vary significantly by region and availability can be limited.
Private access is available through registered online healthcare providers following a clinical assessment—often faster but at a cost. Before pursuing any weight loss treatment, speak with your GP about your weight management goals. They can assess your BMI using our free BMI calculator, discuss your health, and advise on the best route for you—whether NHS services, prescription medication, or lifestyle support.
- 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 lemon water actually help you lose weight?
Lemon water may support hydration and digestion, which are helpful for overall health, but lemon alone does not cause weight loss. Weight loss requires a calorie deficit, typically achieved through dietary changes and physical activity. Lemon can be part of a healthy routine but is not a weight loss solution on its own.
What is the most effective weight loss medication available in the UK?
Mounjaro and Wegovy are both NHS-approved prescription injections. Mounjaro showed slightly higher average weight loss (15–21%) than Wegovy (around 15%) in clinical trials, but individual results vary significantly. Your GP can assess which is more suitable for your specific health situation.
Who is eligible for weight loss injections on the NHS?
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. For South Asian, Black African, or Black Caribbean adults, lower BMI thresholds may apply. Your GP can assess your eligibility.
Can I get prescription weight loss medication privately without waiting?
Yes. Private weight loss prescriptions are available through registered online healthcare providers following a clinical assessment. This is typically faster than NHS referral pathways, though costs vary by provider and dose. Always ensure the provider is GPhC-registered and UK-licensed.
Is weight loss medication prescribed alone, or do I need to change my diet too?
Prescription weight loss medications are most effective alongside a reduced-calorie diet and increased physical activity. Medication supports appetite control and feeling fuller, but does not replace lifestyle changes. Your prescriber will discuss diet and exercise expectations with you.
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.