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
Natural Dietary Supplements for Weight Loss in the UK
Natural dietary supplements are popular for weight management, but evidence for their effectiveness varies significantly. Many people explore herbal remedies, vitamins, and plant-based products as part of their weight loss journey across the UK. However, it's important to understand what the research actually shows and how they compare to evidence-based approaches like prescription weight loss medication or lifestyle changes. Your GP can advise on safety and effectiveness for your individual situation.
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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.
What Do the Studies Show About Natural Supplements?
The evidence for natural dietary supplements is mixed. Some ingredients have modest research support, whilst others lack strong clinical evidence. Green tea extract contains catechins that may modestly increase fat oxidation, though weight loss effects are typically 1–3 kg over several months. Caffeine can increase metabolism slightly and is supported by reasonable evidence, but effects are small. Conjugated linoleic acid (CLA) and glucomannan (a soluble fibre) show some promise in clinical trials, but results are variable and individual.
Ingredients like garcinia cambogia (hydroxycitric acid) and green coffee bean extract have limited robust evidence despite marketing claims. The NHS advises that most natural supplements alone are not effective for significant weight loss. Weight loss typically requires a reduced-calorie diet and increased physical activity — supplements may provide only marginal additional benefit.
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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.
How Do Natural Supplements Compare to Prescription Weight Loss?
Prescription weight loss medications like GLP-1 injections (Mounjaro and Wegovy) produce significantly larger weight loss effects than natural supplements. Clinical trials show GLP-1 medications help users lose 15–21% of body weight on average, alongside lifestyle changes. Natural supplements typically produce 2–5 kg weight loss at best.
GLP-1 medications work by activating hormone pathways that regulate appetite and blood sugar, whilst most natural supplements have much more modest metabolic effects. For weight management in the UK, the NHS weight loss pathway prioritises lifestyle change first, then considers prescription medication for eligible adults. Always discuss natural supplements with your GP before use, as some interact with medications or health conditions.
- 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.
Do natural weight loss supplements actually work?
Some natural ingredients show modest effects in research — green tea extract, caffeine, and glucomannan have the strongest evidence. However, weight loss is typically 2–5 kg at best. Most experts agree lifestyle changes (diet and exercise) provide larger, more sustainable results than supplements alone.
Are natural supplements safer than prescription weight loss medication?
"Natural" does not automatically mean safe. Some supplements can interact with medications, affect blood pressure, or cause side effects. Prescription medications like GLP-1 injections undergo rigorous clinical trials and regulatory approval. Always check with your GP before using any supplement, especially if you take other medicines.
Can I use natural supplements alongside GLP-1 weight loss medication?
This depends on the specific supplement and medication. Some interactions are possible. If you're taking prescription weight loss medication, inform your GP or prescriber about any supplements you're considering. They can advise whether it's safe to combine them.
What does the NHS say about natural weight loss supplements?
The NHS acknowledges some supplements may provide modest benefits but emphasises that evidence is limited. The NHS weight management pathway prioritises calorie reduction, physical activity, and behaviour change first, then considers prescription medication for eligible adults with BMI over 30 or 27+ with health conditions.
How do I know if a weight loss supplement is evidence-based?
Look for clinical trial evidence published in peer-reviewed journals, not marketing claims. Check the ingredient dose — studies often use higher doses than commercial products contain. Use our free BMI calculator to track your baseline, then monitor actual weight change over 8–12 weeks using our progress tracker to assess real effectiveness.
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.