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
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Weight Loss Regime In Gym — UK Medication Options
A structured weight loss regime in the gym works best when combined with sustainable lifestyle changes — and for some adults, prescription medication can support your efforts. If you're interested in weight management UK options, several prescription medications are now available to eligible adults. This guide explains the licensed options, how to know if you qualify, and how to discuss weight loss medication with your GP.
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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
Three prescription-only medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All work by mimicking natural hormones that regulate appetite and fullness. Mounjaro and Wegovy are once-weekly injections; Saxenda is a daily injection. Clinical trials show these medications may help users lose an average of 15–21% of body weight when used alongside a reduced-calorie diet and increased physical activity — though individual results vary significantly. To be eligible for prescription weight loss medication in the UK, you typically need a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Your GP or a licensed prescriber will assess your individual circumstances before recommending any medication.
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 Options
In the NHS, prescription weight loss medication is typically accessed through specialist tier 3 weight management services — not standard GP prescription. Waiting times for NHS specialist services vary significantly by region and can be lengthy. Private access is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. Use our free BMI calculator above to check your starting point, and our GLP-1 weight loss calculator to see potential outcomes at different doses. The most important step is speaking with your GP or a prescriber about whether medication is appropriate for your specific health situation.
- 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.
Can I take weight loss medication if I only go to the gym occasionally?
Prescription weight loss medications work best alongside regular physical activity and a reduced-calorie diet. You don't need to be a regular gym user — any increase in movement combined with dietary changes supports better outcomes. Your prescriber will assess your individual readiness and lifestyle.
What's the difference between Mounjaro and Wegovy for gym-goers?
Both are once-weekly injections. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trial data suggests Mounjaro may support slightly larger average weight loss, but individual results vary. Your prescriber will recommend the most suitable option for you.
How long does it take to see weight loss results with medication?
Most people begin to notice changes within 2–4 weeks, with more significant results over 12–16 weeks. Weight loss is gradual and sustainable — the NHS recommends losing 0.5–1 kg per week. Combining medication with your gym regime and dietary changes optimises results.
Do I need to stop my gym routine to be eligible for weight loss medication?
No. In fact, continuing or starting a gym routine while taking prescription weight loss medication is encouraged. The combination of medication, physical activity, and a reduced-calorie diet produces the best health outcomes and sustainable weight loss.
What's the first step if I want to explore weight loss medication through the NHS?
Speak with your GP about your weight management goals and ask about referral to your local specialist weight management service. Be honest about your current activity level and diet. Your GP will assess whether you meet eligibility criteria and can discuss both NHS and private options available to 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.