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 Should I Take For Weight Loss?
If you're exploring weight loss options, you may wonder whether supplements can help. The truth is that most over-the-counter supplements have limited scientific evidence for significant weight loss. While some may offer modest support alongside diet and exercise, prescription weight loss medication and lifestyle changes remain the most effective approaches for sustainable results. This guide covers evidence-based supplements, their realistic benefits, and how they fit into a broader weight management strategy in the UK.
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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.
Common Weight Loss Supplements and What the Evidence Shows
Several supplements are marketed for weight loss, but evidence varies considerably. Caffeine may increase metabolism slightly and boost exercise performance, though effects are modest. Green tea extract contains catechins that some studies suggest may support fat oxidation, but results are inconsistent. Glucomannan, a soluble fibre, may help you feel fuller for longer and reduce calorie intake slightly. Conjugated linoleic acid (CLA) has mixed evidence for modest fat loss.
The challenge with all these supplements is that effects are typically small — often 1–3 kg over several months — and they work best alongside a reduced-calorie diet and physical activity. Importantly, supplements are not regulated as strictly as medications in the UK, so quality and purity can vary. Always check that any supplement carries a quality mark or has been independently tested. For weight management in the UK, your GP can advise on evidence-based approaches or refer you to NHS weight management services if appropriate.
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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.
Supplements vs Prescription Weight Loss Options
If you're seeking more significant weight loss support, prescription options offer stronger evidence. GLP-1 weight loss medications like Wegovy (semaglutide) and Mounjaro (tirzepatide) work through different mechanisms than supplements — they regulate appetite hormones and may support feeling fuller after smaller meals. Clinical trials showed that adults taking these medications alongside reduced-calorie diet and increased physical activity lost an average of 15–21% of body weight, far more than any supplement alone.
Prescription weight loss medication requires a clinical assessment and a prescription from a licensed healthcare professional. Access is available through NHS specialist weight management services or private online prescribing in the UK. Use our GLP-1 weight loss calculator to understand potential outcomes at different doses, and check your BMI using our free BMI calculator to explore whether you may be eligible for prescription options.
Building a Sustainable Weight Loss StrategyThe most effective weight loss strategy combines several elements: a calorie deficit (typically 500 kcal/day for gradual 0.5 kg/week loss), regular physical activity, and behavioural changes. Supplements may play a minor supporting role, but they should never replace these foundations. If you're considering any supplement — or exploring prescription weight loss medication — speak to your GP first. They can assess your individual health, check for interactions with any existing medications, and advise on what's most appropriate for you.
For long-term success, track your progress consistently. Our free progress tracker lets you log weight changes, dietary choices, and activity levels, helping you stay motivated and identify patterns. Remember that weight loss is rarely linear, and individual results vary widely. Small, sustainable changes supported by evidence-based approaches — whether lifestyle, supplements, or prescription medication — offer the best chance of lasting success.
- 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 weight loss supplements actually work?
Some supplements have modest evidence for supporting weight loss when combined with diet and exercise, but effects are typically small (1–3 kg over months). Green tea extract, glucomannan, and caffeine show some research support, though results vary. Prescription weight loss medication offers significantly stronger evidence — clinical trials show 15–21% average weight loss. Supplements alone are unlikely to produce meaningful results without lifestyle changes.
What's the difference between supplements and prescription weight loss medication?
Supplements are over-the-counter products with limited regulation and modest evidence for weight loss effects. Prescription weight loss medications like Wegovy and Mounjaro are rigorously tested, require clinical assessment, and show much stronger evidence in clinical trials. They work through hormone regulation rather than metabolism boosting. Prescription options are only available following a GP assessment or consultation with a licensed prescriber.
Are weight loss supplements safe?
Many weight loss supplements are safe for most people when used as directed, but quality varies — the UK doesn't regulate supplements as strictly as medicines. Always check for a quality mark or independent testing. However, some supplements may interact with existing medications or health conditions. Before starting any supplement, speak to your GP or pharmacist, especially if you're on other medications or have underlying health conditions.
How much weight can I expect to lose with supplements?
Realistic expectations matter. Research suggests most weight loss supplements contribute to 1–3 kg loss over several months when combined with a reduced-calorie diet and exercise. The NHS recommends losing 0.5–1 kg per week as a sustainable target. For larger weight loss goals, prescription medication combined with lifestyle changes offers stronger evidence — our GLP-1 weight loss calculator shows potential results with prescription options.
Should I try supplements or ask my GP about prescription weight loss options?
Both are valid discussions to have with your GP. If you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions, you may be eligible for prescription weight loss medication in the UK. Your GP can assess your individual circumstances, discuss supplements and prescription options, and refer you to NHS weight management services if appropriate. Consider calculating your BMI first using our free tool.
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.