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 Your BMR? A Complete UK Health Guide
Your BMR (basal metabolic rate) is the number of calories your body burns at rest, just to maintain basic functions like breathing, circulation, and cell production. Understanding your BMR is essential for healthy weight management, as it forms the foundation of any weight loss or fitness plan. In the UK, knowing your BMR helps you make informed decisions about diet and exercise, and it's particularly relevant if you're considering weight management options. This guide explains what BMR means, how it's calculated, and how it relates to your overall health.
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.
How Is BMR Calculated and What Factors Affect It?
BMR is calculated using formulas that account for your age, sex, height, and current weight. The most common formula used in the UK is the Mifflin-St Jeor equation, which is more accurate than older methods. For men, the calculation is: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women, it's: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161.
Several factors affect your BMR: age (BMR decreases by about 2% per decade after 20), sex (men typically have higher BMR than women due to greater muscle mass), muscle mass (muscle tissue burns more calories than fat tissue), genetics (some people naturally have faster or slower metabolism), and hormones (thyroid function and other hormonal factors significantly influence metabolic rate). Your GP can assess whether underlying health conditions are affecting your metabolism if you have concerns.
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.
BMR vs TDEE — Understanding Your Total Daily Energy Expenditure
BMR is just the foundation — your Total Daily Energy Expenditure (TDEE) is what actually matters for weight management. TDEE includes your BMR plus all the calories you burn through daily activities and exercise. For example, if your BMR is 1,500 calories per day, but you work a desk job with light activity, your TDEE might be around 1,800 calories. If you're more active, it could be 2,200 calories or higher.
To lose weight sustainably, the NHS recommends creating a calorie deficit of around 500 calories per day, which typically results in losing about 0.5 kg (1 lb) per week. Use our free BMI calculator and weight converter to understand your current weight context, then calculate your TDEE to plan a realistic, healthy approach to weight management alongside any lifestyle changes you're making.
- 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's a normal BMR for UK adults?
A normal BMR varies widely depending on age, sex, weight, and muscle mass. For an average UK adult woman aged 30, BMR might be around 1,400–1,600 calories per day. For an average UK adult man aged 30, it's typically 1,700–1,900 calories per day. These are approximate ranges — your individual BMR depends on your specific body composition and metabolism.
How does BMR relate to weight management?
Your BMR determines the minimum calories your body needs to function. If you consume fewer calories than your TDEE (which includes BMR plus activity), you'll create a deficit and lose weight. Understanding your BMR helps you set realistic calorie targets. The NHS recommends a deficit of around 500 calories per day for sustainable weight loss of approximately 0.5 kg weekly.
Can BMR change over time?
Yes. BMR decreases naturally with age (roughly 2% per decade after age 20), but you can increase it by building muscle through strength training. Weight loss itself can temporarily reduce BMR slightly, which is why maintaining muscle mass during weight loss is important. Hormonal changes, medical conditions, and certain medications can also affect your metabolic rate.
Does BMR matter if I'm considering weight loss medication?
Yes. Understanding your baseline calorie needs (BMR) helps you see how weight loss medications work alongside diet and exercise. Medications like GLP-1 injections (Wegovy) or dual GIP/GLP-1 injections (Mounjaro) are prescription-only and work by reducing appetite and supporting feeling fuller — they're most effective when combined with a reduced-calorie diet, and knowing your BMR helps you plan realistic intake targets.
How is BMR different from metabolic rate?
BMR is your resting metabolic rate — calories burned at complete rest. Metabolic rate typically refers to your overall metabolism, which includes activity. Resting Metabolic Rate (RMR) is very similar to BMR but slightly higher, as it's measured after light activity rather than complete rest. For practical purposes in UK health guidance, BMR and RMR are often used interchangeably.
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.