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
Pre Workout Supplements and Weight Loss — What You Need to Know
Pre workout supplements are designed to boost energy and exercise performance, not to support weight management. If you're looking for evidence-based weight loss support in the UK, prescription medication may be an option. This guide explains the difference between supplements and clinically-proven weight management options, including which medications are available on the NHS and privately, and how to find out if you're eligible.
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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.
UK-Licensed Weight Loss Medications for Weight Management
If you're interested in weight loss medication rather than supplements, the UK has three prescription-only options licensed for weight management:
- Mounjaro (tirzepatide) — a once-weekly injection that acts as a dual GIP and GLP-1 receptor agonist, with clinical trials showing average weight loss of 15–21% of body weight alongside diet and exercise
- Wegovy (semaglutide) — a once-weekly GLP-1 injection, with clinical evidence showing average weight loss of around 15% of body weight
- Saxenda (liraglutide) — a daily GLP-1 injection, offering similar weight loss support to other GLP-1 medications
All three are prescription-only and require a clinical assessment to determine eligibility. Our GLP-1 weight loss calculator can help you understand potential outcomes if you're considering this option, and your BMI will be one of the key eligibility factors.
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 vs Private — How to Access Weight Loss Medication in the UK
NHS access: Weight loss medications are available through NHS specialist tier 3 and tier 4 weight management services, typically following a GP referral. However, availability and waiting times vary significantly by region, with some areas facing long delays.
Private access: GLP-1 medications are available through private online prescribing services following a clinical assessment by a UK-licensed prescriber. This route does not require an NHS referral and is generally faster, though there is a cost.
To find out if you're eligible, your first step is a conversation with your GP about weight management options for your health situation. They can assess your BMI, discuss your health goals, and explain whether prescription treatment might be suitable for you.
- 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 pre workout supplements effective for weight loss?
Pre workout supplements are designed to enhance exercise performance and energy, not weight loss. While regular exercise is important for weight management, supplements alone do not produce weight loss. Evidence-based weight loss requires a calorie deficit, usually achieved through dietary changes and physical activity combined.
What makes someone eligible for prescription weight loss medication in the UK?
Generally, adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or heart disease, may be eligible. South Asian, Chinese, Black African, and Black Caribbean adults may qualify at slightly lower BMI thresholds. A healthcare professional must assess your individual circumstances.
How much weight can you lose with Mounjaro or Wegovy?
Clinical trials showed average weight loss of around 15–21% of body weight with Mounjaro and around 15% with Wegovy, achieved over several months alongside reduced-calorie diet and increased activity. However, individual results vary significantly, and weight loss is not assured. Your progress depends on your personal circumstances, adherence, and lifestyle changes.
Can I get Mounjaro or Wegovy on the NHS?
Yes, both are available through NHS specialist weight management services. However, access requires a GP referral to tier 3 services and availability varies considerably by region. Waiting times can be several months or longer. Private prescribing is also available without an NHS referral but involves a cost.
What should I do if I'm interested in prescription weight loss treatment?
Start by speaking to your GP about your weight management goals and health history. They can assess whether prescription medication is appropriate for you, refer you to NHS services if eligible, or discuss private options. You can also use our free BMI calculator to check your current BMI as a starting point for the conversation.
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.