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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Best Lifts for Weight Loss — UK Prescription Options
While strength training is excellent for building muscle and supporting weight loss, prescription weight management medication available in the UK can help you achieve faster results. This guide covers the prescription weight loss options available to eligible UK adults—Mounjaro, Wegovy, and Saxenda—and how they work alongside exercise like weightlifting. Whether you're interested in NHS weight loss support or private prescription options, understand what's available 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
Three prescription-only weight loss medications are currently licensed in the UK for weight management. Each works differently and may support your fitness goals when combined with exercise and dietary changes.
- Mounjaro (tirzepatide) — A once-weekly injection that activates dual GIP and GLP-1 hormone pathways. In clinical trials, participants lost an average of 15–21% of their body weight alongside lifestyle changes. Maximum dose: 15 mg weekly.
- Wegovy (semaglutide) — A once-weekly GLP-1 injection. Clinical trial data showed average weight loss of approximately 15% body weight. Maximum dose: 2.4 mg weekly.
- Saxenda (liraglutide) — A daily GLP-1 injection. Available at doses up to 3 mg daily. Results vary, but evidence supports modest weight loss alongside lifestyle modification.
All three require a prescription from a UK-licensed prescriber following a clinical assessment. Eligibility is assessed individually based on your BMI, health conditions, and medical history. Individual results vary significantly—these figures are averages from clinical studies.
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.
Who Can Access Weight Loss Medication in the UK?
You may be eligible for prescription weight loss treatment in the UK if you have a BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may have access at slightly lower BMI thresholds due to higher health risks at lower weights.
Access routes: NHS access is through specialist tier 3 weight management services (referral from your GP required; waiting lists vary by region). Private access is available through GPhC-registered online prescribing services following an online clinical assessment. Your GP can advise you on NHS pathways and eligibility. Use our free BMI calculator to check your personal BMI, then discuss weight loss options with your healthcare provider.
- 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 use weight loss injections while doing strength training?
Yes. Weight loss medications like Mounjaro and Wegovy are designed to be used alongside lifestyle changes including exercise. Strength training supports muscle retention during weight loss. Always inform your prescriber about your exercise routine and any other medications you're taking to ensure safety.
How quickly will I lose weight with prescription medication?
Individual results vary significantly. Clinical trials show average weight loss of 15–21% body weight over several months to a year, but some people lose less and some more. Weight loss typically occurs gradually as doses increase. Sustainable loss is recommended at 0.5–1 kg per week alongside diet and exercise.
What's the difference between Mounjaro and Wegovy?
Both are once-weekly injections for weight management. Mounjaro (tirzepatide) activates dual GIP and GLP-1 pathways and may have slightly higher average weight loss in trials. Wegovy (semaglutide) activates GLP-1 only. Maximum doses differ (15 mg vs 2.4 mg). A prescriber will assess which is more suitable for you.
How do I get weight loss medication on the NHS?
Ask your GP for a referral to your local specialist weight management service (tier 3). These services assess eligibility and manage prescription treatment. Waiting lists vary significantly by region—some areas have long waits. Your GP can advise you on local availability and NHS weight loss support options.
Are there side effects with weight loss injections?
Common side effects include nausea, diarrhoea, constipation, and stomach pain—particularly when starting or increasing doses. Most people adjust after a few days. Serious side effects are rare but include severe stomach pain and gallbladder problems. Your prescriber will discuss all risks and benefits before you start treatment.
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.