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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Macro Calculator for Weight Loss: UK Medication Context
A macro calculator helps you track protein, carbohydrates, and fats to support weight management. In the UK, many people combine nutrition planning with prescription weight loss medication for better results. This guide explains how macro tracking fits within UK weight management options, including GLP-1 medications like Mounjaro and Wegovy, NHS weight loss support, and when to speak to your GP about prescription weight loss options available to eligible adults.
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 Options
If you're tracking macros as part of a weight management UK plan, prescription medications may support your efforts if you're eligible. Three prescription weight loss options are licensed in the UK:
- Mounjaro (tirzepatide) — A once-weekly injection that activates two natural hormone pathways (GIP and GLP-1). Clinical trials showed participants lost an average of 15–21% body weight alongside reduced-calorie diet and increased activity. Starting dose 2.5mg, maximum 15mg weekly.
- Wegovy (semaglutide) — A once-weekly GLP-1 injection. Average weight loss in trials was approximately 15% body weight at the maximum 2.4mg dose.
- Saxenda (liraglutide) — A once-daily GLP-1 injection, maximum 3mg per day.
Eligibility: Adults with BMI weight loss needs of 30 or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease). Ethnicity-adjusted lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. All require prescription and clinical assessment.
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: How to Find Out If You're Eligible
NHS route: Ask your GP about referral to a tier 3 specialist weight management service. NHS access is available but varies significantly by region — waiting lists can be lengthy. Private route: GPhC-registered online pharmacies offer prescription weight loss medication following a clinical assessment with a UK-licensed prescriber, without NHS referral.
Macro calculators track daily nutrition, but weight loss injections UK work by reducing appetite and supporting feeling fuller. Combined with your macro targets and the free BMI calculator on this page, you can understand your starting point and track progress. Use our GLP-1 weight loss calculator to estimate potential results at different doses if you're exploring medication options. Talk to your GP about whether prescription weight loss medication is right for you — they can assess your individual health and eligibility.
- 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.
Do I need a macro calculator if I'm taking weight loss medication?
Macro tracking is helpful for supporting overall nutrition quality, but prescription weight loss medications like Mounjaro and Wegovy work through appetite regulation, not macro restriction. Many people find medication makes it easier to eat smaller portions naturally. Combining tracked nutrition with medication may optimise results, but the medication works independently of macro counting. Your GP or prescriber can advise what suits your approach.
What's the difference between tracking macros and taking prescription weight loss medication?
Macro tracking monitors your intake of protein, carbs, and fats—it's a nutrition tool. Prescription weight loss medication (GLP-1 injections) reduces appetite and food cravings through hormone pathways. They work differently: macros are about what you eat, medication is about how much you want to eat. Many people combine both for best results.
How do I know if I'm eligible for NHS weight loss medication in the UK?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Ask your GP about referral to a specialist weight management service. Lower BMI thresholds apply if you're of South Asian, Chinese, Black African, or Caribbean heritage. Your GP will assess your individual situation.
Can I get prescription weight loss injections privately in the UK without NHS referral?
Yes. GPhC-registered online pharmacies can issue prescriptions for Mounjaro, Wegovy, and Saxenda following an online clinical assessment with a UK-licensed prescriber. This is faster than NHS routes but involves private cost. Always ensure you use a registered pharmacy and that a proper clinical assessment is completed before prescription.
What should I discuss with my GP about weight loss medication?
Ask about your eligibility based on BMI and any weight-related health conditions. Discuss whether NHS specialist services or private prescription options suit you. Mention any other medications you take, as some interactions are possible. Explain your goals and ask whether GLP-1 medication (Mounjaro or Wegovy) or other weight management support is appropriate for you. Your GP can help you access the right service pathway.
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.