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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Good Weight Loss Products in the UK — What Works?
Finding effective weight loss products in the UK means understanding what's evidence-based and what actually works for weight management. From NHS-supported digital tools to prescription medications, there are several approaches available depending on your health needs and circumstances. This guide covers the main weight loss products and programmes available to UK adults, helping you understand your options and what might be appropriate for you.
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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.
Prescription Weight Loss Medications Available in the UK
The UK's most established prescription weight loss products are GLP-1 receptor agonist medications, which are available through NHS specialist services or private prescribing following a clinical assessment. The main options include:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist injected once weekly. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly.
- Wegovy (semaglutide) — a GLP-1 receptor agonist also injected once weekly. The STEP clinical trial demonstrated average weight loss of approximately 15% of body weight at 68 weeks, alongside a reduced-calorie diet and increased physical activity.
- Saxenda (liraglutide) — a daily GLP-1 injection, though less commonly prescribed than the once-weekly options.
All three are prescription-only medicines requiring assessment by a UK-licensed prescriber to determine suitability based on your individual health circumstances. GLP-1 weight loss injections work by helping reduce appetite, increase feelings of fullness, and may help regulate blood sugar control—effects that support weight management when combined with lifestyle changes.
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.
Other Evidence-Based Weight Loss Approaches
Beyond prescription medications, several other weight loss products and programmes are available across the UK. The NHS weight management pathway includes digital programmes, structured community weight loss services, and behavioural support through tier 1 and 2 services. Check our free BMI calculator to understand your starting point and whether you might be eligible for NHS or private weight loss support.
Low-calorie replacement products (such as meal replacement shakes and sachets) can support a structured calorie deficit approach—typically aiming for approximately 500 kcal daily deficit to achieve sustainable loss of around 0.5 kg per week. Fitness and activity trackers, combined with food logging apps, provide tools for monitoring progress. Our free progress tracker helps log weight changes and spot trends over time, while the weight converter makes it easy to track your weight in stone, kg, or lbs—whichever suits you best.
- 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.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are prescription-only injections given once weekly, but Mounjaro (tirzepatide) uses a dual mechanism affecting GIP and GLP-1 pathways, whilst Wegovy (semaglutide) affects GLP-1 only. Clinical trials suggest both may support weight loss averaging 15–21% of body weight, though individual results vary. A prescriber can advise which might be suitable for your specific circumstances.
Are prescription weight loss injections available on the NHS?
Yes, tirzepatide (Mounjaro) and semaglutide (Wegovy) are available through NHS specialist tier 3 weight management services, but access varies significantly by region and availability. Waiting lists can be lengthy. Private prescribing through GPhC-registered pharmacies offers an alternative route without NHS referral, following an online clinical assessment.
How quickly will I lose weight with these products?
Clinical trials show average weight loss over 68–72 weeks, but individual results vary significantly based on adherence, diet, activity, and metabolism. NHS guidelines recommend sustainable loss of 0.5–1 kg per week. A prescriber can discuss realistic timelines based on your health profile. Our GLP-1 weight loss calculator can help estimate potential outcomes at different doses.
Do I need to change my diet and exercise with weight loss medications?
Yes—weight loss medications work best alongside a reduced-calorie diet and increased physical activity. Clinical trials showed these results were achieved with lifestyle changes. Medication supports these changes but is not a substitute for them. Your GP or prescriber can discuss a realistic plan tailored to your circumstances.
What's the difference between Wegovy and Ozempic?
Both contain semaglutide, but Wegovy is specifically licensed for weight management in the UK (doses up to 2.4 mg), whilst Ozempic is licensed for type 2 diabetes management (up to 2 mg). Using Ozempic for weight loss is off-label and not recommended. Always ensure you're prescribed the correct licensed product for your intended use.
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.