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 Reduction Pills in the UK
Weight reduction pills are prescription-only medications available in the UK to support weight management in adults with obesity or excess weight-related health conditions. These medications work alongside lifestyle changes like diet and exercise. If you're considering weight reduction pills, understanding your options, NHS eligibility, and how they work is essential. This UK health guide covers what you need to know about prescription weight management medications currently available through the NHS and private prescribing.
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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.
NHS-Approved Weight Reduction Pills and How They Work
Prescription weight reduction pills in the UK include GLP-1 receptor agonist injections and other weight management medications. The most commonly prescribed options are tirzepatide (Mounjaro) and semaglutide (Wegovy), both licensed by the MHRA for weight management. These medications work by helping regulate appetite, reducing food cravings, and supporting you to feel fuller after smaller meals. They are not appetite suppressants in the traditional sense—instead, they mimic natural hormones your body produces. All weight reduction pills are prescription-only and require a clinical assessment by a GP or licensed prescriber before being dispensed. NICE (National Institute for Health and Care Excellence) has approved tirzepatide for use within NHS specialist weight management services, though access varies significantly by region and local availability.
- Weight reduction pills are prescription-only medications—not available over the counter
- NHS access is typically through tier 3 specialist weight management services, not standard GP prescribing
- Private prescribing is available through GPhC-registered online pharmacies following an online consultation
- Results must be combined with a reduced-calorie diet and increased physical activity for best outcomes
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.
UK Eligibility and Next Steps
You may be eligible for prescription weight reduction pills in the UK if you have a BMI of 30 or above, or a BMI of 27–29.9 with a weight-related health condition such as type 2 diabetes, high blood pressure, or cardiovascular disease. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, eligibility may begin at a lower BMI threshold. To check your personal BMI and understand where you fall on the NHS health scale, use our free BMI calculator above. If you think you may be eligible, the next step is to speak with your GP about referral to a specialist weight management service, or to explore private prescribing options. Your GP can also discuss whether weight reduction pills are appropriate for your individual health situation.
Weight reduction pills are not a structured approach—they work best as part of a comprehensive approach to weight management. Individual results vary; clinical trials show that people taking these medications alongside lifestyle changes lose on average 15–21% of their body weight, though some lose more and some less. To track your progress and estimate potential weight loss outcomes, try our free GLP-1 weight loss calculator. It's also helpful to use our weight converter to track your weight in both kg and stone as you progress. Remember, sustainable weight loss typically occurs at a rate of 0.5–1 kg per week according to NHS guidance. Always consult your GP before starting any weight reduction medication, and be honest about your health history, current medications, and any concerns you have.
- 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 weight reduction pills available on the NHS?
Yes, weight reduction pills (tirzepatide and semaglutide) are available on the NHS through specialist tier 3 weight management services. However, availability and waiting times vary significantly by region. Your GP can refer you to your local specialist service. Many people also access these medications privately through GPhC-registered online pharmacies.
What's the difference between weight reduction pills and appetite suppressants?
Weight reduction pills like GLP-1 medications work differently to older appetite suppressants. They mimic natural hormones and help regulate hunger signals, reduce cravings, and slow digestion—not just suppress appetite. They also support better blood sugar control and are licensed for medical use, whereas some older appetite suppressants are no longer recommended.
Do I need to change my diet if I take weight reduction pills?
Yes. Weight reduction pills work best alongside a reduced-calorie diet and increased physical activity. The medication supports your efforts, but lifestyle changes are essential. Without dietary changes, weight loss results are significantly reduced. Your GP or a dietitian can help you develop a sustainable eating plan.
What are the side effects of weight reduction pills?
Common side effects include nausea, diarrhoea, constipation, and stomach discomfort, especially when starting or increasing doses. These usually improve over time. Serious side effects are rare but can include pancreatitis or gallbladder problems. Always discuss potential side effects with your prescriber before starting treatment.
How do I know if weight reduction pills are right for me?
A licensed prescriber will assess your medical history, current health conditions, medications, and weight to determine suitability. Eligibility is based on BMI and health factors. Use our free BMI calculator to check your starting point, then discuss options with your GP or a private prescriber who can provide personalised medical advice based on your individual 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.