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
Clean Eating for Weight Loss in the UK
Clean eating can support sustainable weight loss, but for many people in the UK, combining dietary changes with prescription weight management medication offers more effective results. If you're carrying excess weight and struggling despite healthy eating habits, prescription options like Mounjaro and Wegovy are now available through the NHS and private providers. This guide explains how clean eating fits into an overall weight loss uk strategy, and what medication options may be available to you based on your BMI and health circumstances.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Medication Available in the UK
Three UK-licensed prescription medications can support weight loss alongside clean eating and physical activity:
- Mounjaro (tirzepatide) — A once-weekly injection that works by activating GLP-1 and GIP hormone pathways. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks.
- Wegovy (semaglutide) — A once-weekly GLP-1 injection. Trial data showed average weight loss of around 15% of body weight at the maximum dose.
- Saxenda (liraglutide) — A daily GLP-1 injection, typically reserved when other options are unsuitable.
You may be eligible if your BMI is 30 or above, or 27 or above with a weight-related health condition (type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease). For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply. All three medications are prescription-only and require clinical assessment before being prescribed. Individual results vary significantly — weight loss medication works best alongside clean eating and increased physical activity, not as a replacement for lifestyle changes.
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
NHS access: Available through specialist tier 3 weight management services following a GP referral. Availability and waiting times vary significantly by region. Contact your GP to ask about specialist weight management services in your area.
Private access: Available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. Private treatment can be faster but involves out-of-pocket costs.
Whether you choose NHS or private provision, your weight loss journey will be most successful when combining clean eating, increased physical activity, and — if eligible — prescription support. Use our free BMI calculator above to check your current BMI and understand where you stand relative to NHS thresholds. Our GLP-1 weight loss calculator can help you estimate potential weight loss at different medication doses if you're considering prescription options.
- 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 clean eating alone help me lose weight without medication?
Yes, clean eating can support sustainable weight loss, especially combined with physical activity and a calorie deficit of around 500 kcal per day (typically resulting in 0.5–1 kg loss per week). However, if you have a BMI over 30 or weight-related health conditions, prescription medication may significantly improve your results. Your GP can advise whether medication is appropriate for you.
What does "clean eating" mean for weight loss?
Clean eating typically means choosing whole, unprocessed foods — lean proteins, vegetables, fruits, whole grains, legumes, and healthy fats — whilst minimising processed foods, added sugars, and excessive salt. It's not about restriction but about nutrient-dense choices that keep you satisfied and support a healthy calorie deficit.
How does Mounjaro or Wegovy work alongside clean eating?
These GLP-1 medications reduce appetite and help you feel fuller after smaller meals, making it easier to maintain a calorie deficit. They're not a replacement for clean eating — they work best when combined with it. Weight loss injections support your dietary efforts by managing hunger and cravings.
Am I eligible for prescription weight loss medication on the NHS?
You may be eligible if your BMI is 30 or above, or 27 or above with a weight-related health condition such as type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease. Contact your GP for an assessment. Lower BMI thresholds apply for certain ethnic backgrounds.
How long does it take to see results with clean eating and medication combined?
Most people notice appetite reduction within 1–2 weeks of starting medication. Measurable weight loss typically becomes apparent within 2–4 weeks. However, results vary between individuals. The NHS recommends sustainable weight loss of 0.5–1 kg per week. Patience and consistency with both clean eating and medication are key.
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.