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
Fibre-Rich Diet for Weight Loss — UK Health Guide
Eating more fibre can support weight loss by helping you feel fuller for longer and stabilising blood sugar levels. A fibre-rich diet is one of the most evidence-backed dietary approaches for sustainable weight management in the UK. Alongside lifestyle changes like increased physical activity, adding more vegetables, whole grains, and legumes to your meals can make a real difference. However, if you've tried dietary changes and are still struggling with your weight, prescription weight management options may be worth exploring with your GP. Use our free BMI calculator to check your current health status and understand your eligibility for support.
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.
UK Prescription Weight Management Options Available
For adults who qualify, the NHS and private prescribers in the UK offer licensed weight management medications alongside diet and lifestyle changes. Mounjaro (tirzepatide) is a once-weekly injection that may help reduce appetite and support weight loss through dual hormone action. Wegovy (semaglutide) is another once-weekly injection approved for weight loss in UK adults. Both are prescription-only medicines available through NHS specialist services or private clinical assessment.
- Eligibility: BMI of 30 or above, or 27–29.9 with weight-related health conditions
- Access: Through NHS tier 3 weight management services or private prescribers following assessment
- Clinical evidence: Clinical trials showed average weight loss of 15–21% body weight alongside diet and exercise
- Important: Individual results vary significantly, and medications work best combined with a fibre-rich diet and physical activity
Try our free GLP-1 weight loss calculator to see projected weight loss estimates at different doses if you're considering prescription options.
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.
Next Steps — Speak to Your GP About Your Weight
If a fibre-rich diet alone hasn't delivered the results you want, your GP can discuss whether prescription weight loss medication is suitable for you. They'll review your BMI, medical history, and weight-related health conditions to determine eligibility. On the NHS, you may be referred to a tier 3 specialist weight management service, though waiting lists vary by region. Alternatively, private online prescribing is available without an NHS referral — but still requires a clinical assessment from a UK-licensed prescriber. Whatever route you choose, combining any medication with dietary improvements, increased fibre intake, and regular activity gives the best chance of sustainable weight loss.
- 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 a high-fibre diet alone help me lose weight?
Yes, a fibre-rich diet supports weight loss by promoting fullness, stabilising blood sugar, and reducing overall calorie intake. However, sustainable weight loss typically requires a modest calorie deficit alongside fibre intake and physical activity. If dietary changes aren't producing results, speak to your GP about prescription options.
What are the main sources of dietary fibre for weight loss?
Whole grains, vegetables (especially leafy greens and broccoli), legumes (beans and lentils), fruits with skins, nuts, and seeds are all excellent fibre sources. Aim for at least 30g of fibre daily according to NHS guidance. Adding these gradually helps your digestive system adapt.
Am I eligible for prescription weight loss medication on the NHS in the UK?
You may be eligible if your BMI is 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Eligibility is assessed individually. Ask your GP for a referral to your local tier 3 weight management service.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections licensed for weight loss in the UK. Mounjaro (tirzepatide) uses a dual hormone mechanism and clinical trials showed average weight loss of 15–21%. Wegovy (semaglutide) is a single GLP-1 agonist with average weight loss around 15%. Individual results vary, and your prescriber will advise which suits you.
How quickly will I see weight loss results on prescription medication?
Weight loss typically begins within 2–4 weeks but varies between individuals. Most people see gradual loss over 12–16 weeks as doses are increased. Results are best when combined with a fibre-rich diet, calorie reduction, and regular physical activity. Track your progress with our free progress tracker.
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.