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
Weights vs Cardio: Which Is Better for Weight Loss in the UK?
Both weights and cardio play important roles in weight management in the UK. Cardio burns calories quickly and improves heart health, while resistance training builds muscle, which increases your resting metabolic rate. For sustainable weight loss, combining both is typically most effective. However, exercise alone rarely achieves significant weight loss without dietary changes. For eligible adults, prescription weight loss medication available through the NHS or private prescribing can accelerate results when paired with lifestyle changes. Our free GLP-1 weight loss calculator can help you explore how medication might support your weight management goals alongside exercise.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Prescription Weight Loss Options in the UK
For adults struggling with weight management, prescription medications are available in the UK alongside diet and exercise. Three GLP-1 and GIP/GLP-1 receptor agonist medications are licensed for weight loss:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 injection administered once weekly, licensed for adults with a BMI of 30 or above, or 27+ with weight-related health conditions
- Wegovy (semaglutide) — a GLP-1 injection given once weekly, with similar eligibility criteria
- Saxenda (liraglutide) — a GLP-1 injection administered daily, for adults meeting the same eligibility thresholds
Clinical trials show these medications may support weight loss of 15–21% of body weight on average alongside reduced-calorie diet and physical activity. Individual results vary significantly. These are prescription-only medicines requiring clinical assessment before being prescribed. Use our BMI calculator above to check your starting point — this helps assess eligibility for prescription weight management options.
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 Prescribing in the UK
Access to prescription weight loss medication in the UK follows two main routes. NHS access is through specialist tier 3 or tier 4 weight management services, typically requiring a GP referral and assessment. Availability and waiting times vary significantly by region. Private prescribing is available through GPhC-registered online pharmacies following an online clinical assessment, without requiring NHS referral.
Whichever route you choose, a licensed prescriber will assess whether medication is clinically appropriate for you based on your individual health, medical history, and BMI. Your GP can discuss eligibility and recommend the most suitable weight management approach — combining exercise, diet, and medication where appropriate. Track your progress with our free progress tracker to monitor results over time.
- 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 lose weight with weights or cardio alone without medication?
Yes — both weights and cardio can contribute to weight loss. Cardio typically burns more calories per session, while weights build muscle and increase resting metabolism. However, sustainable weight loss requires a calorie deficit, primarily through diet. Exercise accelerates results but is most effective when combined with reduced calorie intake. For eligible adults, medication alongside exercise and diet can amplify results.
What's the difference between Mounjaro and Wegovy?
Both are once-weekly injections for weight management. Mounjaro is a dual GIP and GLP-1 receptor agonist that activates two hormone pathways, with clinical trials showing average weight loss of 15–21% of body weight. Wegovy is a GLP-1-only agonist with average weight loss around 15%. Both require prescription. Your prescriber will assess which suits you better based on individual health factors.
How do I know if I'm eligible for prescription weight loss medication in the UK?
You may be eligible if your BMI is 30 or above, or 27+ with a weight-related health condition (such as type 2 diabetes, high blood pressure, or obstructive sleep apnoea). Eligibility is assessed individually by a licensed prescriber through NHS specialist services or private online consultations. Use our free BMI calculator to check your current BMI, then discuss options with your GP.
Do I still need to exercise if I take prescription weight loss medication?
Yes. Prescription weight loss medications work best alongside reduced-calorie diet and physical activity. Medication supports appetite regulation and makes it easier to maintain a calorie deficit, but exercise provides cardiovascular, mental health, and metabolic benefits that medication alone does not offer. Combining both achieves the best results.
How do I access prescription weight loss medication through the NHS?
Ask your GP for a referral to your local specialist weight management service (tier 3). These services provide assessment, prescription, and ongoing monitoring. Availability varies by region — some areas have long waiting lists. Alternatively, private online prescribing through a GPhC-registered service may offer faster access. Your GP can advise on both routes based on your circumstances.
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.