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
How To Work Out Your Basal Metabolic Rate
Your basal metabolic rate (BMR) 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 helpful for weight management and healthy weight loss planning. This UK health guide explains the formulas, shows you how to calculate yours, and describes how BMR relates to your overall daily calorie needs and weight loss goals.
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.
BMR Formulas and How to Calculate Yours
The most commonly used formula for calculating BMR is the Mifflin-St Jeor equation, which is more accurate than older methods like Harris-Benedict. This formula accounts for your weight in kilograms, height in centimetres, age in years, and biological sex.
For men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
For women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
For example, a 35-year-old woman who is 165cm tall and weighs 70kg would calculate: (10 × 70) + (6.25 × 165) − (5 × 35) − 161 = 700 + 1,031 − 175 − 161 = 1,395 calories per day at rest. This represents the minimum energy your body needs daily before any physical activity is accounted for.
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.
Understanding BMR in Weight Management Context
Your BMR is different from your total daily energy expenditure (TDEE). Your TDEE includes your BMR plus calories burned through physical activity and digestion. To lose weight sustainably, the NHS recommends creating a calorie deficit through a combination of reduced-calorie diet and increased physical activity. Knowing your BMR helps you understand how many calories you can safely reduce. For most people, a deficit of approximately 500 calories per day supports losing around 0.5kg per week. Use our free BMI calculator to check your current health status, and track your progress with our weight loss progress tracker as you work towards your goals.
- 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 the difference between BMR and TDEE?
BMR is calories burned at complete rest. TDEE (total daily energy expenditure) includes BMR plus activity calories. For weight loss, you need to know both figures to calculate safe calorie deficit. Your GP or a nutritionist can help you establish appropriate targets based on your individual health.
Does BMR change with age?
Yes, BMR decreases with age by approximately 2–8% per decade after age 30, because muscle mass naturally declines. This is why older adults may find weight management requires different strategies. Regular strength exercise can help maintain muscle and support BMR.
Can BMR be increased?
Building lean muscle through strength training increases BMR because muscle tissue burns more calories at rest than fat tissue. Regular physical activity, adequate protein intake, and sufficient sleep also support a healthier metabolic rate. However, dramatic increases are not realistic.
Why do men and women have different BMR formulas?
Men typically have more muscle mass and less body fat than women on average, so they burn more calories at rest. This is why the female formula includes an additional −161 factor. Individual variation is significant, so these are estimates, not exact measurements.
Should I use BMR or TDEE for weight loss planning?
Use TDEE for weight loss planning because it accounts for your actual daily activity. Never eat below your BMR, as this risks nutrient deficiency and muscle loss. The NHS recommends a moderate deficit of 500 calories daily from your TDEE for sustainable 0.5kg weekly loss.
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.