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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Alcohol and Weight Loss — What You Need to Know
Alcohol can significantly impact weight loss efforts because it contains calories, may increase appetite, and often leads to eating more high-calorie foods. If you're considering weight management in the UK, understanding how alcohol affects your progress is important — especially if you're exploring prescription options like Mounjaro or Wegovy. This guide explains the relationship between alcohol and weight loss, and outlines the prescription weight loss medications available to eligible adults in the UK.
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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 for Weight Management
For adults struggling with weight management, three prescription medications are licensed in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are GLP-1 and dual GIP/GLP-1 receptor agonist medications that support appetite reduction and feeling fuller after eating.
Eligibility in the UK: You may be eligible if you have a BMI of 30 or above, or 27 or above with weight-related health conditions (type 2 diabetes, high blood pressure, cardiovascular disease). For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower thresholds may apply. All these medications are prescription-only and require a clinical assessment before being prescribed.
Clinical evidence shows these medications support meaningful weight loss when used alongside a reduced-calorie diet and increased physical activity. Use our free GLP-1 weight loss calculator to see potential projections at different doses, and check your BMI with our free calculator to understand your starting point.
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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 Access vs Private Prescription — How to Get Started
NHS route: Referral to a tier 3 specialist weight management service through your GP. Availability varies significantly by region, and waiting times can be lengthy in many areas.
Private route: Prescription issued following an online clinical assessment with a UK-licensed prescriber, dispensed by a GPhC-registered pharmacy. Available without NHS referral.
To find out if you're eligible, speak with your GP about weight management options. They can discuss your health history, assess whether prescription medication is appropriate, and explain what support is available through the NHS in your area. If alcohol consumption is affecting your weight, your GP can also provide support with reducing intake.
Q1: Does alcohol prevent weight loss? A1: Yes, alcohol can significantly slow weight loss. It contains calories (approximately 7 per gram), may increase appetite, and often leads to poor food choices. Reducing alcohol intake can support better weight management outcomes, especially when combined with prescription weight loss medication or lifestyle changes. Q2: Can I drink alcohol while taking Mounjaro or Wegovy? A2: There are no absolute contraindications, but moderation is important. These medications can cause nausea and stomach upset, and alcohol may worsen these side effects. Always discuss alcohol consumption with your prescriber during your clinical assessment, as they can provide personalised guidance based on your individual health. Q3: How much weight can I expect to lose with UK prescription medications? A3: Clinical trials show Mounjaro (tirzepatide) helped participants lose an average of 15–21% of body weight, and Wegovy (semaglutide) showed approximately 15% average loss. Individual results vary significantly. Weight loss is achieved alongside a reduced-calorie diet and increased physical activity — medication supports but does not replace lifestyle changes. Q4: Am I eligible for prescription weight loss treatment on the NHS? A4: You may be eligible if you have a BMI of 30 or above, or 27 or above with weight-related health conditions. Access is through specialist tier 3 weight management services, typically by GP referral. Eligibility varies by region and availability. Speak with your GP to discuss whether this option is suitable for you. Q5: What's the difference between Mounjaro and Wegovy for weight loss? A5: Both are prescription-only weekly injections. Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist with higher average weight loss (15–21%), while Wegovy (semaglutide) is a GLP-1 agonist with approximately 15% average loss. Clinical evidence and individual suitability differ — your prescriber will assess which 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.
What is BMI and how is it calculated?
BMI (Body Mass Index) is calculated by dividing your weight in kilograms by your height in metres squared. It's the standard screening tool used by the NHS to assess whether adults are a healthy weight.
Is BMI accurate for everyone?
BMI is a useful screening tool but doesn't account for muscle mass, bone density, or body fat distribution. Athletes may have a high BMI without excess fat. The NHS recommends using BMI alongside waist circumference for a more complete picture.
What are GLP-1 medications like Mounjaro and Wegovy?
GLP-1 receptor agonists are prescription medications that mimic gut hormones to reduce appetite and help with weight loss. Mounjaro (tirzepatide) and Wegovy (semaglutide) are the two most widely used for weight management in the UK.
Am I eligible for GLP-1 weight loss medication in the UK?
Generally, you need a BMI of 30+ (obese) or 27+ with a weight-related health condition. You must be 18 or over. Use our BMI calculator to check.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist with up to 22.5% weight loss. Wegovy (semaglutide) is GLP-1-only with up to 15-17% weight loss. Both are weekly injections.
Is this website free to use?
Yes, 100% free. No sign-up required. All tools work instantly in your browser and no personal data is stored on our servers.
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.