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
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Carnivore Diet Weight Loss — UK Prescription Options
The carnivore diet — eating only animal products — is followed by some people hoping to lose weight. However, sustainable weight loss and weight management in the UK increasingly involves prescription options. If you're interested in the carnivore diet or any weight loss approach, it's worth knowing about UK-licensed prescription medications that may support your goals alongside dietary changes. This guide covers the prescription weight management options available to eligible UK adults, how they work, and how to find out if you might be suitable.
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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 Prescription Weight Loss Medications
Three prescription-only weight management injections are currently licensed in the UK for adults with excess weight:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist, administered once weekly. Clinical trials showed participants lost an average of 15–21% of body weight, though individual results vary significantly.
- Wegovy (semaglutide) — a GLP-1 receptor agonist, also once weekly. Evidence suggests average weight loss of around 15% of body weight when used alongside a reduced-calorie diet and increased physical activity.
- Saxenda (liraglutide) — a GLP-1 receptor agonist administered as a daily injection.
All three are prescription-only medicines requiring clinical assessment. Your BMI, health conditions, and individual circumstances determine eligibility. These medications are typically used alongside dietary changes — not instead of them — making them compatible with various eating approaches, including low-carbohydrate or carnivore-style diets.
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 in the UK
NHS access: Prescription weight loss treatment is available through specialist tier 3 weight management services. You'll need a referral from your GP, and access varies significantly by region. NHS waiting lists can be lengthy in many areas.
Private access: Available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. This route does not require an NHS referral and may have shorter waiting times, though costs apply (typically £120–£320 per month depending on dose).
To find out if you're eligible, calculate your BMI using our free BMI calculator, then speak with your GP about your options — whether that's NHS referral or exploring private prescribing pathways.
- 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 use prescription weight loss medication if I follow a carnivore diet?
Yes, prescription weight loss medications like Mounjaro and Wegovy work alongside any dietary approach. They're typically prescribed alongside a reduced-calorie diet and increased physical activity. Always discuss your current eating approach with your prescriber during assessment.
What is the BMI threshold for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (such as type 2 diabetes, high blood pressure, or sleep apnoea), may be eligible. Use our free BMI calculator to check your BMI instantly.
How long does it take to see results with prescription weight loss injections?
Results vary individually. Most people begin noticing changes within the first 4–8 weeks, though meaningful weight loss typically develops over months. Clinical trials tracked results over 68–72 weeks. Patience and consistency are important.
What's the difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 agonist (maximum dose 15 mg weekly), while Wegovy is a GLP-1 agonist only (maximum dose 2.4 mg weekly). Clinical trial data suggests Mounjaro achieved slightly higher average weight loss, but results vary between individuals.
How do I get a prescription for weight loss medication on the NHS?
Ask your GP for a referral to your local specialist weight management service (tier 3). They will assess your eligibility and manage your treatment. Waiting times and availability vary by region — contact your local integrated care board for information.
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.