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
Glucomannan Complex and Weight Loss in the UK
Glucomannan is a natural soluble fibre supplement that some people use as part of weight management, though evidence for significant weight loss is limited. If you're looking for effective weight loss support in the UK, prescription medications are available for eligible adults. This guide covers UK-licensed weight loss options, who qualifies, and how to access them through the NHS or privately. Understanding all available approaches—from dietary changes to evidence-backed medications—helps you make an informed decision about weight management.
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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
For adults with a BMI of 30 or above (or 27 or above with weight-related health conditions), three prescription weight loss medications are licensed in the UK:
- Mounjaro (tirzepatide) — dual GIP and GLP-1 injection, once weekly, doses 2.5–15 mg. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks alongside reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide) — GLP-1 injection, once weekly, doses 0.25–2.4 mg. Average weight loss approximately 15% of body weight in clinical trials.
- Saxenda (liraglutide) — GLP-1 injection, daily dosing, doses 0.6–3 mg. Effective for weight management though requires daily administration.
All three are prescription-only medicines. Individual results vary, and these medications work best alongside lifestyle changes. Our free GLP-1 weight loss calculator can help you estimate potential outcomes at different doses if you're considering this option.
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.
Accessing Weight Loss Medication: NHS vs Private
NHS route: Referral to a specialist tier 3 weight management service through your GP. Access varies by region and can involve waiting lists. Your GP can assess your eligibility and discuss whether prescription weight loss treatment is appropriate for you.
Private route: Online consultation with a UK-licensed prescriber, prescription issued if clinically suitable, dispensed by a GPhC-registered pharmacy. Available without NHS referral, typically faster access, but costs approximately £129–£320 monthly depending on dose.
If glucomannan or other supplements haven't delivered results, starting a conversation with your GP about prescription options is a practical next step. Use our free BMI calculator to understand your current BMI status and discuss eligibility criteria with your healthcare provider.
- 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.
Is glucomannan effective for weight loss?
Glucomannan is a soluble fibre that absorbs water and may promote feelings of fullness. Some research shows modest weight loss support (typically under 3 kg in clinical studies), but effects are generally modest compared to prescription medications. It's best used as part of a broader weight management strategy.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist with average weight loss of 15–21%, while Wegovy (semaglutide) is a GLP-1 agonist with average weight loss around 15%. Both are once-weekly injections. Mounjaro uses higher doses (up to 15 mg) compared to Wegovy (up to 2.4 mg). Individual results vary significantly.
How do I know if I'm eligible for prescription weight loss medication in the UK?
You may be eligible if your BMI is 30 or above, or 27 or above with a weight-related health condition (diabetes, high blood pressure, heart disease, etc.). Your GP or a licensed prescriber can assess your individual circumstances. Use our free BMI calculator above to check your current BMI.
How much do prescription weight loss injections cost privately in the UK?
Private costs typically range from £129–£320 per month depending on the medication and dose. NHS access is free but varies by region and involves specialist referral. Prices change regularly, so check with individual providers for current pricing.
Can I switch from one weight loss injection to another?
Switching between medications (e.g., from Mounjaro to Wegovy) is possible but must be managed by your prescriber. There's no official conversion chart—any change requires clinical assessment. Never change doses or switch medications without guidance from your healthcare provider.
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.