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
Keto Diet Plan for Weight Loss in the UK
A keto diet plan is a low-carbohydrate, high-fat eating approach that may support weight loss alongside other lifestyle changes. However, for many UK adults with excess weight, prescription weight management medication has shown strong clinical evidence for supporting weight loss. If you're considering a keto diet or exploring other weight loss options, it's worth understanding what prescription options are available through the NHS or private prescribing, and whether you might be eligible for support beyond diet alone.
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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 Options
If you have a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes or high blood pressure, you may be eligible for prescription weight loss medication in the UK. Three licensed options are currently available:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks, alongside diet and exercise.
- Wegovy (semaglutide) — a GLP-1 receptor agonist. The STEP trial demonstrated average weight loss of approximately 15% of body weight.
- Saxenda (liraglutide) — a GLP-1 receptor agonist taken as a daily injection, with similar evidence for weight loss support.
All three are prescription-only and require a clinical assessment to establish suitability. Results vary between individuals, and these medications work best combined with reduced-calorie diet and increased physical activity — similar to how a keto diet plan works within a broader weight management approach.
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
In the UK, access to prescription weight loss medication differs between NHS and private routes. NHS access is through specialist tier 3 weight management services — your GP can refer you, though waiting times and availability vary significantly by region. Private access is available through UK-licensed online prescribers following a remote clinical assessment, without NHS referral.
To find out if you're eligible, calculate your BMI using our free BMI calculator above. If your BMI suggests you might benefit from assessment, speak with your GP about either NHS referral or ask whether private prescribing options are available in your area. A prescriber can assess your individual health and discuss whether prescription medication, a keto diet plan, or a combination of approaches is right for you.
- 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 a keto diet plan instead of prescription weight loss medication?
Yes — a keto diet plan is a valid approach for some people and may support sustainable weight loss. However, prescription weight loss medication has stronger clinical evidence for significant weight loss in people with obesity or overweight with health conditions. Many UK adults benefit from combining dietary approaches with medication support. Your GP can help you decide which approach suits your circumstances.
How do I know if I'm eligible for prescription weight loss treatment on the NHS?
NHS eligibility typically requires a BMI of 30 or above, or 27 or above with weight-related health conditions. Use our free BMI calculator on this page to check your BMI, then speak with your GP about referral to specialist weight management services in your area. Waiting times vary by region.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are prescription-only injections, but Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trials showed Mounjaro achieved slightly higher average weight loss (15–21%) compared to Wegovy (around 15%), though individual results vary considerably.
How quickly can I expect to lose weight on prescription medication?
Weight loss typically becomes noticeable within 4–8 weeks, with more significant results after 12–16 weeks. Safe and sustainable weight loss is generally 0.5–1 kg per week. Results depend on the medication dose, adherence to diet and exercise, and individual factors. Our progress tracker can help you log your journey.
Can I combine a keto diet plan with prescription weight loss medication?
Yes — prescription medications are designed to work alongside dietary changes and increased physical activity. Many people combine structured eating approaches like keto with medication for enhanced results. Always discuss your diet plan with your prescriber to ensure compatibility with your chosen medication. ```
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.