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
What Is Muscle Gauge and Why Does It Matter?
Muscle gauge is a measure of the percentage of your body weight that is made up of muscle tissue, as opposed to fat, bone, and water. Unlike BMI, which only uses height and weight, muscle gauge gives you a more detailed picture of your body composition. This matters for health because two people at the same weight can have very different muscle-to-fat ratios, affecting their strength, metabolism, and overall wellness. Understanding your muscle gauge helps you assess whether weight changes reflect fat loss or muscle gain—crucial information that standard weight measurements alone cannot provide.
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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.
How Muscle Gauge Differs From BMI
BMI (body mass index) is a simple calculation using only height and weight—it cannot distinguish between muscle and fat. Two people with identical BMI can have completely different body compositions. Someone who lifts weights regularly may have a high BMI but low body fat percentage, while someone sedentary at the same BMI may have high body fat and low muscle mass. This is why muscle gauge is a more complete picture of health. Muscle tissue is metabolically active, meaning it burns calories even at rest, while fat tissue does not. Higher muscle mass supports better metabolism, bone density, and functional fitness. For this reason, NHS guidance on healthy weight increasingly emphasises body composition alongside BMI. Use our free BMI calculator alongside muscle gauge assessment for the most comprehensive view of your health status.
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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.
How to Measure and Track Muscle Gauge
There are several methods to estimate or measure muscle gauge: DEXA scans (gold standard, available through NHS in some regions), bioelectrical impedance analysis (BIA) (scales and handheld devices, moderate accuracy), skinfold calipers (requires trained technician), and prediction formulas (based on age, weight, height—less accurate). For consistent tracking, the same method should be used each time. Many gyms offer free or low-cost body composition scans. If you're tracking weight loss or fitness progress, our free progress tracker helps you log changes over time alongside other health metrics. Regular muscle gauge measurement is especially valuable if you're following a weight loss or fitness programme, as it shows whether you're losing fat while preserving muscle—a key marker of healthy, sustainable progress.
- 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 a good muscle gauge percentage for adults in the UK?
Healthy muscle percentage varies by age and sex. For adult men, 30–40% muscle mass is typical; for women, 20–30%. These ranges decline with age. Individual targets depend on fitness goals and activity level. Your GP or a qualified fitness professional can advise on targets relevant to your health.
Does muscle gauge matter more than BMI?
Both have value. BMI screens for weight-related health risks at population level. Muscle gauge gives personal detail about body composition. For comprehensive health assessment, use both together. Our free BMI calculator and weight converter help you understand both metrics in UK measurements.
Can I improve my muscle gauge?
Yes. Resistance training (weights, bodyweight exercises) builds muscle. Adequate protein intake supports muscle maintenance during weight loss. Progressive strength work over weeks and months increases muscle mass. Combined with a healthy diet, consistent training significantly improves muscle gauge over time.
Is high muscle mass always healthy?
Generally yes, but context matters. Healthy muscle gain from training is beneficial. Extreme muscle gain pursued through unsafe methods or steroids carries health risks. Always prioritise sustainable, evidence-based approaches and consult your GP if making major changes.
How does muscle gauge relate to weight loss injections like Mounjaro or Wegovy?
GLP-1 medications help reduce body fat, but they don't build muscle directly. Combining medication with strength training and adequate protein helps preserve muscle during weight loss. Tracking muscle gauge during treatment shows whether fat loss is happening while muscle is maintained—important for long-term health outcomes.
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.