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
Best gradual weight management Diet in the UK
gradual weight management often requires more than diet alone. In the UK, prescription weight loss medications like Mounjaro and Wegovy are now available for eligible adults as part of a comprehensive weight management strategy. These medicines work alongside dietary changes and increased physical activity to support faster results. The NHS recognises that some people benefit from medication-assisted weight management, particularly those with a BMI of 30 or above, or 27–29.9 with weight-related health conditions. This guide explains your UK options and how to find out if you're eligible.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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
Three prescription-only medicines are currently licensed in the UK for weight management, available through both NHS specialist services and private prescribing:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 injection, given once weekly, with clinical trials showing average weight loss of 15–21% of body weight over 72 weeks
- Wegovy (semaglutide) — a GLP-1 receptor agonist, once-weekly injection, with average weight loss of approximately 15% of body weight in clinical trials
- Saxenda (liraglutide) — a daily GLP-1 injection, offering similar effectiveness to Wegovy but requiring daily administration
These are not diet pills — they are prescription injectable medications that work by regulating appetite and helping you feel fuller after smaller meals. All three are used alongside a reduced-calorie diet and increased physical activity. Individual results vary significantly. You can try our free GLP-1 weight loss calculator to explore projected weight loss at different medication doses.
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 Eligibility and How to Access Weight Management Support
In the UK, you may be eligible for prescription weight loss medication if you have a BMI of 30 kg/m² or above, or 27–29.9 kg/m² with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or cardiovascular disease. Lower BMI thresholds may apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage due to higher health risks at lower weights.
NHS route: Ask your GP for a referral to a specialist tier 3 weight management service. Waiting lists vary by region and can be lengthy. Private route: Online consultations with UK-licensed prescribers are available without NHS referral, though costs apply. Either way, a prescriber will assess your individual health and determine suitability. Use our free BMI calculator to check your starting point, then discuss your options with your GP.
- 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.
Is gradual weight management safe?
The NHS recommends losing 0.5–1 kg per week for sustainable, safe weight loss. Faster loss is possible with medical support but increases muscle loss risk. Prescription medications support faster loss when combined with diet and exercise, but rapid loss without medical supervision is not recommended.
Can I get prescription weight loss medication on the NHS?
Yes, Mounjaro and Wegovy are available through NHS specialist weight management services. Access requires referral from your GP and varies by region. Many areas have long waiting lists. Private access is available without NHS referral through UK-licensed prescribers.
How much weight do these medications actually help you lose?
In clinical trials, Mounjaro achieved average weight loss of 15–21% of body weight, and Wegovy approximately 15%, over several months. Results vary widely between individuals. These medicines work best combined with a reduced-calorie diet and physical activity — they are not standalone solutions.
What's the difference between Mounjaro and Wegovy?
Mounjaro is a dual GIP and GLP-1 agonist; Wegovy is GLP-1-only. Mounjaro achieved slightly higher average weight loss in trials (21% vs 15%), but both are effective. Which suits you depends on individual health factors — a prescriber will assess suitability.
Are there side effects to prescription weight loss injections?
Common side effects include nausea, diarrhoea, constipation, and stomach discomfort, usually mild and temporary. Rare serious side effects include pancreatitis. A prescriber will review your full health history and discuss all risks before prescribing. ``` --- ## CONTENT NOTES **Semantic keyword integration:** - "weight management uk" — naturally in intro and section 2 - "nhs weight loss" — in section 3 (NHS eligibility) - "lose weight uk" — in intro and throughout - "glp-1 weight loss" — in section 2 (medication descriptions) - "weight loss injections uk" — in section 2 heading - "prescription weight loss uk" — in section 3 - "weight loss medication nhs" — in section 3 (NHS route) - "bmi weight loss" — in section 3 (BMI eligibility context) **Tool references:** - GLP-1 weight loss calculator → naturally in Section 2 (COL_H) as users want to explore projected outcomes - BMI calculator → naturally in Section 3 (COL_J) to help users check their starting point before GP conversation **Angle delivery:** ✅ Section 2 covers UK-licensed options (Mounjaro, Wegovy, Saxenda) with clinical evidence ✅ Section 3 addresses NHS vs private access and how to determine eligibility ✅ Encourages GP conversation throughout ✅ Redirects from "diet" angle to medication + diet combined approach (as per angle instructions) **Compliance:** ✅ No pharmacy names mentioned ✅ Prescription-only status clearly stated ✅ Conditional language ("may", "can help", "clinical trials showed") ✅ Individual results vary acknowledged ✅ UK English and measurements throughout ✅ Clinical evidence cited (trial data from CMKB) ✅ Non-judgmental, health-focused tone
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.