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
Fast Weight Loss Tips — UK Prescription Options
If you're looking for fast weight loss tips, prescription weight management medication may be an option worth discussing with your GP. While lifestyle changes remain essential, UK-licensed weight loss injections can support faster results for eligible adults. This guide covers prescription weight management options available in the UK, who can access them, and how to find out if you qualify. Remember, sustainable weight loss typically combines medication with dietary changes and increased physical activity for the best outcomes.
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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 Available Now
Three prescription-only medications are currently licensed in the UK for weight management:
- Mounjaro (tirzepatide) — a once-weekly injection with dual GIP and GLP-1 action. Clinical trials showed average weight loss of 15–21% of body weight alongside reduced-calorie diet and physical activity.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection. Evidence suggests average weight loss of around 15% of body weight in clinical trials.
- Saxenda (liraglutide) — a daily GLP-1 injection, less commonly prescribed in current UK practice.
All three are prescription-only medicines requiring a clinical assessment before being prescribed. Individual results vary significantly. Use our free GLP-1 weight loss calculator to estimate potential results at different doses, and our BMI calculator to check your personal baseline.
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 and Eligibility
You may be eligible for prescription weight loss medication if you have a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Lower BMI thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage.
NHS access: Referral through your GP to a tier 3 specialist weight management service. Availability and waiting times vary significantly by region.
Private access: Through GPhC-registered online prescribing services following a clinical assessment. No NHS referral needed. Costs typically range from £129–£320 monthly depending on dose.
Start by speaking to your GP about whether prescription weight loss treatment is right 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.
What's the fastest safe weight loss rate with medication?
The NHS recommends losing no more than 0.5–1 kg (1–2 lbs) per week for sustainable results. GLP-1 medications may support faster loss initially, but individual rates vary. gradual weight management can increase muscle loss and nutritional risks, so always follow your prescriber's guidance and maintain a balanced diet.
Do I need to diet and exercise if I take weight loss medication?
Yes. Weight loss medications work best alongside a reduced-calorie diet and increased physical activity. Clinical trials showing average 15–clinically studied weight loss were achieved by participants who also made lifestyle changes. Medication alone is less effective than medication plus behaviour change.
How quickly will I see results with Mounjaro or Wegovy?
Results vary significantly between individuals. Most people notice appetite reduction within the first few weeks, but meaningful weight loss typically takes 8–12 weeks to become apparent. Doses are increased gradually over 16–20 weeks, so full results often take 3–6 months. Track your progress with our free progress tracker.
Can I get weight loss injections on the NHS?
Yes, if eligible and referred to a specialist tier 3 weight management service by your GP. However, NHS availability varies by region and waiting times can be several months. Private prescribing offers faster access without NHS referral, though costs apply. Ask your GP about local options.
What if my BMI is just under 30 — can I still get prescription medication?
Yes, if you have weight-related health conditions (diabetes, high blood pressure, heart disease, sleep apnoea, or high cholesterol). BMI thresholds are also lower for people of South Asian, Chinese, Black African, or Black Caribbean heritage. Check your BMI using our free calculator and discuss eligibility with your GP.
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.