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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Can You Lose Weight in 10 Days? UK Medication Options
Losing a significant amount of weight in just 10 days isn't realistic or safe for most people. However, if you're interested in weight management in the UK, prescription medications like Mounjaro and Wegovy can support gradual, sustainable weight loss when combined with lifestyle changes. The NHS recommends losing 0.5 to 1 kg per week for healthy, lasting results. This guide explains what prescription weight loss medication is available in the UK, who's eligible, and how to start the conversation with your GP about weight management options that work for your circumstances.
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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 Prescription Weight Loss Medications
Three UK-licensed prescription medications are approved for weight management in adults: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All are GLP-1 receptor agonists (or dual GIP/GLP-1 agonists in Mounjaro's case), meaning they work by helping regulate appetite and blood sugar control.
- Mounjaro: Once-weekly injection, doses 2.5–15 mg. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks.
- Wegovy: Once-weekly injection, doses 0.25–2.4 mg. Clinical trials showed average weight loss of approximately 15% of body weight at the maximum dose.
- Saxenda: Daily injection, doses 0.6–3 mg. Typically produces modest weight loss when combined with diet and activity.
To be eligible, you'll need a BMI of 30 or above, or 27 or above with weight-related health conditions like type 2 diabetes or high blood pressure. Eligibility varies slightly for adults of South Asian, Chinese, Black African, or Black Caribbean heritage, with lower BMI thresholds reflecting higher health risks at those weights. These are all prescription-only medicines requiring clinical assessment before being prescribed.
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 in the UK
In the UK, you can access prescription weight loss medication through two routes. The NHS route involves referral to a specialist tier 3 weight management service, typically through your GP. Availability varies significantly by region, and waiting lists can be lengthy in many areas. The private route offers faster access through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber—you don't need an NHS referral. Either way, a qualified prescriber will assess whether weight management medication is suitable for you based on your individual health. Start by discussing your weight management goals with your GP, who can advise on NHS availability in your area or discuss private options. Use our free BMI calculator to check your starting point, and the GLP-1 weight loss calculator to estimate potential results with prescription medication.
- 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.
How much weight can you realistically lose in 10 days?
Most healthy weight loss is 0.5–1 kg per week. In 10 days, you might lose 1–1.5 kg through calorie deficit alone. Prescription medication works over weeks and months, not days. gradual weight management increases muscle loss and isn't sustainable.
Is prescription weight loss medication available on the NHS in the UK?
Yes. Mounjaro, Wegovy, and Saxenda are NHS-approved for eligible adults. Access is through specialist tier 3 weight management services. Your GP can refer you, though waiting lists vary by region. Private access is also available through online prescribing.
Who is eligible for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure, may be eligible. Eligibility criteria are lower for South Asian, Chinese, Black African, and Black Caribbean adults. A prescriber will assess your individual circumstances.
What's the difference between Mounjaro and Wegovy for weight loss?
Mounjaro is a dual GIP/GLP-1 agonist with a maximum dose of 15 mg weekly; clinical trials showed 15–clinically studied weight loss. Wegovy is a GLP-1 agonist with a maximum dose of 2.4 mg weekly; trials showed approximately clinically studied weight loss. Both are once-weekly injections. Results vary individually.
Should I try extreme weight loss methods instead of medication?
No. Very gradual weight management diets (under 800 kcal/day) should only be done under medical supervision and increase risks of nutrient deficiency and muscle loss. Prescription medication combined with moderate calorie deficit and lifestyle changes is a safer, evidence-based approach supported by the NHS.
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.