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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Quick Weight Loss Tips: UK Prescription Options
Losing weight quickly isn't always sustainable, but combining lifestyle changes with prescription weight management can accelerate results for eligible adults. This guide covers the most effective quick weight loss tips available in the UK, including prescription medications, how to check eligibility, and practical steps to get started. We'll help you understand your options through weight management UK services and private 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 Options
Three prescription-only medicines are currently licensed in the UK for weight management:
- Mounjaro (tirzepatide) — A dual GIP and GLP-1 receptor agonist. Once-weekly injection, doses from 2.5 mg to 15 mg. Clinical trials showed average weight loss of 15–21% body weight over 72 weeks when combined with diet and exercise.
- Wegovy (semaglutide) — A GLP-1 receptor agonist. Once-weekly injection, doses from 0.25 mg to 2.4 mg. STEP trial data showed average weight loss of approximately 15% body weight at the maximum dose.
- Saxenda (liraglutide) — A GLP-1 receptor agonist. Once-daily injection. Typically produces 5–clinically studied weight loss.
All three are prescription-only and require a clinical assessment before being dispensed. Eligibility depends on BMI and health factors — use our free BMI calculator above to determine your starting point. These medications work alongside a reduced-calorie diet and increased physical activity; they are not a replacement for 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.
How to Access Weight Loss Medication in the UK
NHS route: Your GP can refer you to a specialist tier 3 or tier 4 weight management service. Eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Waiting times vary significantly by region.
Private route: Online prescribing services can assess your eligibility following a brief consultation. If prescribed, your medication is dispensed by a GPhC-registered pharmacy. This route often has shorter wait times but involves out-of-pocket costs.
Both routes require you to discuss your health with a healthcare professional first. Our GLP-1 weight loss calculator can help you estimate potential results at different doses once you know which medication might suit 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.
What is the quickest way to lose weight in the UK?
The fastest sustainable approach combines a moderate calorie deficit (500 kcal per day), consistent physical activity, and if eligible, prescription weight loss medication. The NHS recommends losing 0.5–1 kg per week. Prescription options like Mounjaro or Wegovy can accelerate this, but they work best alongside diet and exercise changes, not instead of them.
Can I get weight loss injections on the NHS?
Yes, if you meet eligibility criteria. You'll need a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Ask your GP for a referral to your local specialist weight management service. Availability and waiting times vary by region; some areas have significant waiting lists. Private prescribing is an alternative if NHS access is delayed.
How much weight can I lose with Mounjaro or Wegovy?
Individual results vary significantly. Clinical trials showed Mounjaro users lost 15–21% of body weight on average, and Wegovy users lost approximately 15% on average, over 68–72 weeks alongside diet and exercise. Some people lose more, some less. Your personal outcome depends on your starting weight, adherence, and lifestyle changes.
Are weight loss injections safe?
Prescription weight loss medications are safe for most eligible adults when used as prescribed. Common side effects include nausea, diarrhoea, and constipation, which often reduce over time. Serious side effects are rare but can occur. Your prescriber will assess whether the medication is right for you based on your medical history.
What should I do to qualify for prescription weight loss medication?
First, calculate your BMI using our free BMI calculator on this page. If your BMI is 30 or above, or 27–29.9 with weight-related health conditions, you may be eligible. Contact your GP to discuss your options, or explore private prescribing services that can assess your suitability following an online consultation. Either way, a licensed prescriber must evaluate you individually.
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.