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
What Supplements Help With Weight Loss?
If you're looking for ways to support weight loss, you've probably heard about various supplements and pills claiming to help. The truth is that most over-the-counter weight loss supplements have limited evidence behind them in the UK. The most effective approaches for weight management uk combine lifestyle changes with, where appropriate, prescription medication under clinical guidance. Let's explore what actually works and what the NHS recommends for sustainable weight loss.
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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.
Evidence-Based Weight Loss Options in the UK
When it comes to weight loss uk, prescription medications prescribed by your GP or through specialist services are far better researched than supplements. Prescription weight loss options include GLP-1 receptor agonists like Wegovy (semaglutide) and Mounjaro (tirzepatide), which have undergone rigorous clinical trials. Wegovy clinical trials (the STEP studies) showed participants lost an average of around 15% of their body weight over 68 weeks when combined with diet and exercise. Mounjaro demonstrated similar or greater results in the SURMOUNT trials. These are not supplements — they're prescription-only medicines requiring clinical assessment, but they represent the strongest evidence for pharmacological weight loss support available in the UK. Most over-the-counter supplements lack this level of scientific backing and NHS weight loss guidance focuses on lifestyle changes as the foundation.
- Prescription GLP-1 medications have robust clinical trial evidence
- Over-the-counter supplements typically lack strong research support
- Lifestyle changes (diet and exercise) remain the proven foundation
- Your GP can discuss prescription weight loss medication nhs options if appropriate
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.
Natural Lifestyle Approaches and Limited Supplement Evidence
The NHS emphasises that sustainable weight loss comes primarily from reducing calorie intake and increasing physical activity. Some supplements like caffeine, green tea extract, and glucomannan have modest supporting evidence, but effects are typically small — often just a few pounds over many months. Fibre supplements may help with satiety, but whole foods like vegetables and pulses are more effective and nutritious. Our free weight loss calculator can help you estimate realistic weight loss goals based on your individual situation. Before starting any supplement, consult your GP, especially if you're taking other medications. For significant weight loss, bmi weight loss calculators and professional guidance from your healthcare provider will give you a much clearer picture of what's achievable and safe for your circumstances.
- 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 weight loss supplements regulated in the UK?
Weight loss supplements are less strictly regulated than medicines. The UK Medicines and Healthcare products Regulatory Agency (MHRA) regulates medicines, but supplements fall under food law. This means many supplements haven't undergone the rigorous testing required for prescription medications. Always check labels for quality assurance marks and discuss supplements with your GP before starting.
Which supplements have the most evidence for weight loss?
Green tea extract, caffeine, and glucomannan have some research support, but effects are modest — typically 1–3 kg over several months. These work best alongside diet and exercise. Prescription weight loss medications like Wegovy and Mounjaro have far stronger clinical evidence and are prescription-only options available through your GP or specialist services.
Can supplements replace diet and exercise for weight loss?
No. The NHS is clear that sustainable weight loss requires calorie deficit through diet and increased physical activity. No supplement can replace these fundamentals. Prescription medications may support these lifestyle changes, but they work alongside — not instead of — healthy eating and movement.
Is glp-1 weight loss a supplement or medication?
GLP-1 weight loss medications like Wegovy are prescription-only medicines, not supplements. They're far more regulated and have extensive clinical trial evidence. They require a prescription from a licensed prescriber following clinical assessment. They're available through NHS specialist services or private online prescribing in the UK.
What should I do before trying any weight loss supplement?
Always consult your GP first. They can check for interactions with any medications you're taking, assess your overall health, and discuss whether prescription options like glp-1 weight loss injections might be more appropriate for you. Your GP can also advise on diet, exercise, and realistic weight loss goals for your situation.
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.