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
Best Weight Loss Capsules in the UK
When searching for weight loss capsules in the UK, it's important to understand that most effective prescription weight management options are actually injections rather than capsules. Saxenda (liraglutide) is the only GLP-1 receptor agonist available as a capsule-alternative daily injection for weight management. However, prescription weight loss injections like Wegovy (semaglutide) and Mounjaro (tirzepatide) offer superior clinical results and are once-weekly options licensed by the MHRA. This guide covers what's available, how they work, and how to access weight loss medication through NHS weight loss services or private prescription routes. Always consult your GP before starting any weight management treatment.
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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.
How Prescription Weight Loss Medications Work
The most effective weight management medications available in the UK are GLP-1 receptor agonists and dual GIP/GLP-1 agonists, which work by mimicking natural hormones that regulate appetite and blood sugar. Wegovy (semaglutide) is a once-weekly injection that activates GLP-1 pathways, helping you feel fuller after smaller meals and reducing food cravings. In clinical trials (STEP-1), Wegovy helped participants lose an average of 15% of their body weight over 68 weeks — though individual results vary significantly. Mounjaro (tirzepatide) uses a dual GIP and GLP-1 mechanism and showed average weight loss of around 20% in trials. Both are prescription-only medicines requiring a clinical assessment. Unlike traditional diet pills, these medications work with your body's natural hunger regulation systems rather than stimulating the nervous system. They're most effective when combined with reduced-calorie diet and increased physical activity. Use our free GLP-1 weight loss calculator above to estimate potential outcomes at different doses.
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.
Accessing Weight Loss Medication in the UK
In the UK, prescription weight loss medication is available through two main routes. The NHS weight loss pathway involves referral to a tier 3 specialist weight management service from your GP — though availability and waiting times vary significantly by region. Private prescription is faster and doesn't require NHS referral: online consultations with UK-licensed prescribers can assess suitability, and medications are dispensed by GPhC-registered pharmacies. Eligibility typically requires a BMI of 30 or above, or 27 or above with weight-related health conditions like type 2 diabetes, high blood pressure, or cardiovascular disease. Check your personal BMI using our free BMI calculator above to understand where you sit. Both routes require genuine clinical assessment — there are no shortcuts to obtaining prescription weight loss treatment legitimately in the UK.
- 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 there weight loss capsules available in the UK?
Most effective prescription weight loss medications in the UK are injections, not capsules. Saxenda (liraglutide) is a once-daily injection. Wegovy and Mounjaro are once-weekly injections with stronger clinical evidence. Non-prescription capsules and pills lack robust evidence for significant weight loss and are not recommended by the NHS as first-line treatment.
How much weight can I lose with prescription weight loss medication?
Clinical trials showed Wegovy users lost around 15% of body weight on average, while Mounjaro users lost approximately 20%. However, individual results vary significantly based on dose, adherence, diet, and activity level. Always remember these are average outcomes — your results may differ.
Do I need a prescription for weight loss capsules or injections?
Yes. All effective GLP-1 medications (Wegovy, Mounjaro, Saxenda) are prescription-only in the UK. You must be assessed by a qualified healthcare professional before receiving a prescription. This assessment checks your medical history, current medications, and suitability.
What's the difference between Wegovy and Mounjaro?
Both are prescription injections for weight management. Wegovy (semaglutide) activates GLP-1 pathways only. Mounjaro (tirzepatide) activates both GIP and GLP-1 pathways. Clinical trials suggest Mounjaro may produce slightly greater average weight loss, but both are effective. Your prescriber will advise which suits you.
Can I access weight loss medication through the NHS?
Yes, through specialist tier 3 weight management services. Your GP can refer you. However, NHS availability varies by region and waiting lists can be lengthy. Private prescription routes offer faster access without requiring NHS referral, though these involve costs typically ranging from £129–£320 per month depending on dose.
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.