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
7 Week Weight Loss: UK Prescription Medication Options
Achieving meaningful weight loss in seven weeks is possible with the right support, particularly when prescription weight management medication is appropriate for your circumstances. In the UK, several prescription options are available through the NHS or private prescribing, alongside lifestyle changes. Understanding your eligibility and how these medications work can help you make an informed decision about your weight management journey. Using our free BMI calculator above, you can first assess where you currently stand and explore whether prescription support might be suitable 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.
UK-Licensed Weight Loss Medications for 7-Week Results
Three main prescription weight loss medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Mounjaro and Wegovy are once-weekly injections, while Saxenda is a daily injection.
In clinical trials, participants using these medications alongside a reduced-calorie diet and increased physical activity achieved an average weight loss of 15–21% of body weight over several months. Over a seven-week period, results vary significantly depending on your starting weight, dose, and individual response — some people may experience noticeable changes within this timeframe, whilst others progress more gradually.
Eligibility criteria are consistent across all three medications: you may qualify if you have a BMI of 30 or above, or a BMI of 27–29.9 with at least one weight-related health condition (such as type 2 diabetes, high blood pressure, or sleep apnoea). For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply.
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 Started
NHS route: Your GP can refer you to a specialist tier 3 or tier 4 weight management service, where prescription weight loss medication may be offered. However, NHS access varies significantly by region and availability — waiting lists can be substantial in many areas.
Private route: You can access prescription weight loss medication through a UK-licensed online prescriber without an NHS referral. Following a clinical assessment, a prescription can be dispensed by a GPhC-registered pharmacy. This route is faster but involves private costs.
Try our free GLP-1 weight loss calculator above to estimate potential weight loss outcomes at different doses, and use the progress tracker to monitor your actual results over your seven-week period. Start a conversation with your GP about whether prescription weight management support is appropriate for you.
- 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.
Can I lose weight in 7 weeks with prescription medication?
Yes, prescription weight loss medications like Mounjaro and Wegovy may help you achieve noticeable weight loss within seven weeks when combined with a reduced-calorie diet and physical activity. Individual results vary — some people see significant changes whilst others progress more gradually depending on dose, starting weight, and personal response.
What is the NHS pathway for prescription weight loss medication?
In the UK, you can request a referral from your GP to a specialist weight management service (tier 3 or 4). These services assess your eligibility and may prescribe weight loss medication if appropriate. Availability and waiting times vary considerably by region and NHS integrated care board.
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 type 2 diabetes or high blood pressure. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, the BMI threshold is lower (from 27.5). Your GP or prescriber will assess your individual circumstances.
What's the difference between Mounjaro and Wegovy for 7-week weight loss?
Both are once-weekly injections licensed in the UK for weight management. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, whilst Wegovy (semaglutide) is a GLP-1 agonist. Clinical trial data suggests similar average weight loss outcomes, though individual results vary. Your prescriber will recommend the most suitable option.
How quickly will I see weight loss results in 7 weeks?
Weight loss typically becomes noticeable within 2–4 weeks of starting prescription medication, though some people see changes sooner. Over seven weeks, results depend on your dose level and individual response. Most people lose weight gradually and consistently rather than rapidly, which supports healthier, more sustainable outcomes.
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.