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 Scales for Weight Loss: UK Prescription Options
Choosing the right scales is important for tracking your weight loss progress, but equally important is understanding the prescription weight management options available in the UK. For adults with a BMI of 30 or above, or 27 or above with weight-related health conditions, NHS-approved medications may help support your weight loss journey alongside lifestyle changes. This guide covers the best approach to weight tracking and explains how prescription weight loss medication works in the UK health system, from eligibility to access routes.
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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 Prescription Weight Loss Medications
If you're considering prescription weight loss medication in the UK, three main options are currently licensed: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Mounjaro and Wegovy are once-weekly injections, while Saxenda is a daily injection. In clinical trials, these medications have helped people lose significant amounts of weight — Mounjaro showed average weight loss of 15–21% of body weight, and Wegovy around 14–15% — though individual results vary considerably and always occur alongside a reduced-calorie diet and increased physical activity.
Eligibility for prescription weight loss treatment includes adults with a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. All prescription weight loss medications require a clinical assessment before being prescribed. You can check your personal BMI using our free BMI calculator above to see where you fall on the NHS scale.
- Mounjaro: dual GIP and GLP-1 agonist, doses up to 15 mg weekly
- Wegovy: GLP-1 agonist only, doses up to 2.4 mg weekly
- Saxenda: GLP-1 agonist, daily injections up to 3 mg
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 vs Private Access: How to Get Prescription Weight Loss Treatment
In the UK, prescription weight loss medication is available through two routes: NHS specialist weight management services and private online prescribing. NHS access typically involves referral from your GP to a tier 3 or tier 4 specialist service, though availability varies significantly by region and waiting lists can be lengthy in many areas. Private access is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber — this route does not require an NHS referral.
Start by speaking with your GP about whether prescription weight loss treatment is appropriate for your individual circumstances. Your GP can assess your BMI, health conditions, and any medications you're currently taking. They can also advise on NHS access in your area or discuss private options. Using our free GLP-1 weight loss calculator can help you understand the potential outcomes with different medications before your appointment.
- 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 makes good scales for weight loss tracking?
Quality scales should display weight to 0.1 kg (or 0.1 stone) precision, have a stable base, and allow you to track multiple users and trends over time. Digital scales with connectivity to apps are helpful for long-term progress tracking. Consider our free progress tracker tool on this page to log your weight loss journey alongside accurate scale measurements.
Am I eligible for prescription weight loss medication in the UK?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like diabetes or high blood pressure. Some groups, including South Asian and Black African adults, qualify at lower BMI thresholds. Check your BMI using our free calculator above, then speak with your GP about your eligibility.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with average weight loss of 15–21%, while Wegovy (semaglutide) is a GLP-1 agonist only with average weight loss around 14–15%. Individual results vary. Your prescriber will assess which is more suitable for you based on your health profile.
How can I access weight loss medication through the NHS?
Ask your GP for a referral to a specialist tier 3 or tier 4 weight management service in your area. These services provide comprehensive assessment and prescribing. Waiting times vary by region — some services have extended waiting lists. Your GP can advise on timescales and alternatives, including private prescribing options.
Do weight loss medications work without diet and exercise changes?
No. Prescription weight loss medications like Mounjaro and Wegovy work alongside a reduced-calorie diet and increased physical activity — not instead of them. The medication helps manage appetite and reduce cravings, making it easier to sustain the lifestyle changes needed for sustainable weight management. Your GP or prescriber will discuss this during your assessment.
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.