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
Black Coffee and Weight Loss: What the Evidence Shows
Black coffee is often promoted as a weight loss aid, but the evidence is modest. While caffeine may have minor metabolism-boosting effects and can help suppress appetite temporarily, coffee alone won't produce significant weight loss. For meaningful and sustainable weight management in the UK, lifestyle changes — including diet and physical activity — are essential. If you're struggling to lose weight, prescription medications and NHS support may be worth exploring, especially if you have a BMI of 30 or above or weight-related health conditions.
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 Weight Loss Medication Options
If black coffee and lifestyle changes aren't delivering the results you need, several prescription weight loss medications are licensed in the UK for eligible adults. These include Mounjaro (tirzepatide), a dual GIP and GLP-1 receptor agonist, and Wegovy (semaglutide), a GLP-1 receptor agonist. Both are once-weekly injections. Clinical trials showed that Mounjaro helped participants lose an average of 15–21% of their body weight, whilst Wegovy resulted in approximately 14.9% average weight loss — though individual results vary significantly.
To be eligible for prescription weight loss medication in the UK, you typically need 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. These medications are prescription-only and require a clinical assessment before being prescribed.
- Available through NHS specialist weight management services or private online prescribing
- Used alongside reduced-calorie diet and increased physical activity
- Individual eligibility assessed by a prescriber
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.
Getting Started: NHS vs Private Routes
Access to prescription weight loss medication in the UK depends on your route. The NHS route involves a referral to a tier 3 specialist weight management service from your GP, though waiting lists vary significantly by region. The private route is available through GPhC-registered online pharmacies following a clinical assessment — no NHS referral needed.
Start by calculating your BMI using our free BMI calculator above to understand your health status. If you believe you're eligible, speak to your GP about weight management options available to you. Your GP can discuss whether prescription medication, lifestyle support, or NHS specialist services are appropriate for your individual circumstances. A prescriber will assess whether treatment is suitable based on your health, medications, and personal needs.
- 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 black coffee alone help me lose weight?
Black coffee contains caffeine, which may provide minor metabolism support and temporary appetite suppression. However, studies show the effect is modest — typically a 3–4% increase in calorie burn. Weight loss requires a sustained calorie deficit through diet and physical activity. If you're struggling despite lifestyle changes, speak to your GP about evidence-based options.
What is the difference between Mounjaro and Wegovy?
Both are prescription-only GLP-1 medications licensed in the UK for weight management. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with doses up to 15 mg weekly; Wegovy (semaglutide) is a GLP-1 agonist with a maximum dose of 2.4 mg weekly. Clinical trials showed Mounjaro achieved slightly higher average weight loss (15–21%) compared to Wegovy (14.9%), though individual results vary. Your prescriber will determine which is most suitable.
How do I know if I'm eligible for prescription weight loss medication in the UK?
You may be eligible if you have a BMI of 30 or above, or BMI of 27–29.9 with a weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. Use our free BMI calculator to check your BMI instantly. Speak to your GP for a personalised assessment — they can determine eligibility and discuss your options.
What's the difference between NHS and private access to weight loss medication?
NHS access is through specialist tier 3 weight management services, usually via GP referral, though waiting lists vary by region and availability is limited. Private access is through GPhC-registered online pharmacies following an online clinical assessment — faster and available without NHS referral, but involves a cost. Both routes require a prescription from a UK-licensed prescriber.
Will I need to make diet and lifestyle changes if I take weight loss medication?
Yes. Prescription weight loss medications like Mounjaro and Wegovy are designed to be used alongside a reduced-calorie diet and increased physical activity. Medication is a tool to support your efforts, not a replacement for healthy changes. Your prescriber will discuss diet, exercise, and behaviour change as part of your overall weight management plan.
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.