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
Food Supplements For Weight Loss — What Works in the UK
Many people search for food supplements to support weight loss, but if you're struggling with excess weight, prescription weight management options may be more effective. In the UK, several prescription-only medications including Mounjaro and Wegovy are available through NHS weight loss services and private prescribing for eligible adults. This guide explores both supplements and prescription alternatives, helping you understand what evidence supports each approach and how to find out if you might be eligible for prescription treatment.
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-Licensed Prescription Weight Loss Options
If you're interested in weight management in the UK, prescription medications offer evidence-based options that often outperform supplements alone. Mounjaro (tirzepatide) is a once-weekly injection that works as a dual GIP and GLP-1 receptor agonist, helping regulate appetite and support feeling fuller after meals. In clinical trials, it helped participants lose an average of 15–21% of their body weight. Wegovy (semaglutide) is another once-weekly GLP-1 injection, with average weight loss around 14.9% in clinical trials. Saxenda (liraglutide) is a daily GLP-1 injection option. All three are prescription-only and require a clinical assessment to confirm eligibility.
- Mounjaro: starts at 2.5 mg, increases to max 15 mg weekly
- Wegovy: starts at 0.25 mg, increases to max 2.4 mg weekly
- Saxenda: daily injection, up to 3 mg per day
- All work best alongside reduced-calorie diet and increased physical activity
- Individual results vary significantly
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 Access vs Private Prescribing in the UK
Access to prescription weight loss medication differs depending on which route you choose. NHS access is through specialist tier 3 weight management services — your GP can refer you, though waiting lists vary significantly by region and may be lengthy. Private access is available through UK-licensed prescribers via online consultations without NHS referral. Before considering any option, calculate your BMI using our free BMI calculator above to understand where you fall on the NHS eligibility scale. Adults with a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions, may be eligible. Speak to your GP about whether prescription weight management might suit you — they can discuss your individual circumstances and help you explore 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.
Are food supplements effective for weight loss?
Some supplements show modest effects — caffeine, green tea extract, and fibre can support modest weight loss. However, prescription medications like Mounjaro and Wegovy typically produce greater, more reliable results in clinical trials. Supplements work best alongside diet and exercise, just like prescription options.
What's the difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 agonist, while Wegovy is GLP-1 only. Both are once-weekly injections. Clinical trials showed Mounjaro achieved average weight loss of 15–21%, compared to Wegovy's 14.9%. Results vary individually, and either may be appropriate depending on your health profile.
How do I know if I'm eligible for prescription weight loss treatment in the UK?
You may be eligible if your BMI is 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Use our free BMI calculator to check your BMI, then discuss eligibility with your GP or a licensed prescriber.
Can I get Mounjaro or Wegovy through the NHS?
Yes, through specialist tier 3 weight management services. Your GP can refer you. Alternatively, both are available privately through UK-licensed prescribers following an online assessment. NHS availability varies by region.
Should I try supplements first before asking about prescription options?
It depends on your circumstances. If you have a BMI of 30 or above, or 27–29.9 with health conditions, prescription options may be more effective. Speak to your GP — they can advise whether medication, supplements, lifestyle changes, or a combination would be most appropriate for you.
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.