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
Macros for Weight Loss and Muscle Gain
Getting the balance of macronutrients right is essential when you're trying to lose weight while preserving or building muscle. In the UK, most people working toward this goal combine dietary changes with structured exercise and, when eligible, prescription weight loss support. This guide explains macro fundamentals and how to approach weight management as part of a holistic health strategy.
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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.
Understanding Macros and UK Weight Loss Medication
Macronutrients — protein, carbohydrates, and fat — each play a critical role in weight loss while maintaining muscle mass. Protein is essential, typically aiming for 1.6–2.2g per kg of body weight daily to preserve muscle during weight loss. Carbohydrates fuel workouts and should be moderate and timed around activity. Healthy fats support hormone production and satiety.
For eligible UK adults, prescription weight management options like Mounjaro (tirzepatide) and Wegovy (semaglutide) may support this process. These GLP-1 and dual GIP/GLP-1 receptor agonists can help reduce appetite and support adherence to a reduced-calorie diet — which is essential for weight loss. Clinical trials show participants using these medications lost an average of 15–21% body weight alongside dietary changes and exercise. Individual results vary significantly. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses if you're curious about what prescription medication might achieve.
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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 Getting Started in the UK
If you're considering prescription weight loss medication alongside your nutrition and exercise plan, eligibility is based on BMI and health status. UK adults with a BMI of 30 or above, or 27–29.9 with weight-related conditions like type 2 diabetes or high blood pressure, may be eligible. Access in the UK happens through two routes: NHS specialist tier 3 weight management services (via GP referral, though waiting lists can be lengthy) or private prescribing following an online clinical assessment.
Start by checking your current BMI using our free BMI calculator, then speak with your GP about whether prescription support might suit your weight management goals. Your GP can discuss realistic macro targets, referral to specialist services, or other options. Weight loss is most sustainable when nutrition, exercise, and mental health support work together.
- 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 are macros and why do they matter for weight loss and muscle?
Macronutrients (protein, carbs, fats) are the three main nutrients your body needs. Protein is critical for preserving muscle during weight loss, typically 1.6–2.2g per kg daily. Carbs and fats support energy and hormone function. Balancing them helps you lose fat while maintaining muscle mass.
Can prescription weight loss medication help with macro adherence?
Yes. Medications like Mounjaro and Wegovy work by reducing appetite and supporting feeling fuller, which makes it easier to stick to a reduced-calorie diet with appropriate macros. They're prescription-only and used alongside dietary and lifestyle changes, not instead of them.
How do I know if I'm eligible for UK prescription weight loss treatment?
You're typically eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Use our free BMI calculator to check your BMI, then speak with your GP about options. They can assess eligibility and discuss next steps.
Is weight loss medication available on the NHS in the UK?
Yes, tirzepatide (Mounjaro) and semaglutide (Wegovy) are available through NHS specialist weight management services, though access varies by region and waiting lists can be long. Private prescribing is also available following an online clinical assessment.
Should I track macros when using weight loss medication?
Tracking macros is helpful whether you use medication or not — it ensures you're getting enough protein to preserve muscle and eating within your calorie target. Medication reduces hunger, making it easier to maintain macro targets. Your GP or a registered dietitian can guide you on specific targets for your goals. ``` --- ### IMPLEMENTATION NOTES FOR CONTENT TEAM **Semantic Keywords Naturally Woven:** - "weight management uk" — included in intro context ✓ - "nhs weight loss" — referenced in Section 3 with NHS specialist services ✓ - "lose weight uk" — in intro and Section 3 ✓ - "glp-1 weight loss" — Section 2 with clinical context ✓ - "weight loss injections uk" — Section 2 and Section 3 ✓ - "prescription weight loss uk" — Section 2 and Section 3 ✓ - "weight loss medication nhs" — Section 3 with NHS access explanation ✓ - "bmi weight loss" — in Section 3 context and FAQ Q3 ✓ **Tool Cross-References:** 1. **BMI Calculator** — referenced twice: - Section 3: "Check your current BMI using our free BMI calculator" - FAQ
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.