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
BMR Calculator and NHS-Aligned UK Health Information
Your basal metabolic rate (BMR) is the number of calories your body burns at rest each day — a key measure in UK weight management and nutrition planning. While the NHS doesn't provide a dedicated BMR calculator, understanding your BMR helps you determine your daily energy needs and supports informed decisions about weight loss, weight gain, or maintenance. This guide explains BMR, how it's calculated in the UK context, and how it connects to your overall health and weight goals.
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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.
What Is BMR and Why Does It Matter for UK Health?
Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic functions at rest — breathing, circulation, cell production, and nutrient processing. Your BMR accounts for 60–75% of your total daily energy expenditure, making it a crucial figure for weight management.
The most common formulas for calculating BMR are the Harris-Benedict equation (updated in 1984) and the Mifflin-St Jeor equation (considered more accurate for modern populations). Both use your age, height, weight, and sex. Unlike your BMI, which the NHS frequently monitors, BMR is less commonly discussed in routine GP appointments but is valuable for personalised nutrition planning.
- BMR increases with muscle mass and decreases with age
- Men typically have a higher BMR than women due to greater muscle mass
- BMR can vary by up to 20% between individuals with similar measurements
- Severely restricting calories below your BMR can slow metabolism and harm health
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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.
BMR, Weight Management, and NHS UK Health Guidance
The NHS emphasises sustainable weight management through a balanced approach: a moderate calorie deficit (typically 500 kcal/day for about 0.5 kg per week loss) combined with increased physical activity and behavioural support. Knowing your BMR helps you calculate a safe, achievable deficit without dropping below your resting metabolic needs. Your BMR is unique to you — factors including genetics, medical conditions, medications, and hormone levels all influence it.
If you're considering weight loss, use our free BMI calculator to assess your current health status alongside your BMR calculation. For those exploring prescription weight loss medication such as Mounjaro or Wegovy, understanding your baseline metabolism is helpful context. Always consult your GP for personalised advice about your energy needs and any weight management strategy.
- 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 (total daily energy expenditure)?
BMR is calories burned at complete rest. TDEE is your total daily burn, including activity level. TDEE = BMR × activity factor (typically 1.2–1.9). For weight loss, you create a deficit from TDEE, not BMR. Never eat below your BMR long-term — it can harm metabolism and health.
Can I use a BMR calculator instead of consulting my GP about weight management?
A BMR calculator is a useful informational tool, but it's not a replacement for personalised GP advice. Your GP can assess your overall health, medications, medical history, and recommend safe, appropriate strategies. Always discuss weight management plans with your GP or a registered dietitian.
Does the NHS use BMR in weight management services?
The NHS focuses primarily on BMI, waist circumference, and overall health status. BMR is not routinely calculated in standard GP weight management reviews, but specialist tier 3 weight management services may use metabolic assessment as part of a comprehensive evaluation.
How does BMR change as I lose weight?
As you lose weight, your BMR decreases because your body requires fewer calories to maintain a smaller mass. This is called "metabolic adaptation." This is why weight loss can slow over time. Maintaining muscle mass through resistance exercise helps preserve BMR during weight loss.
Should I use BMR to decide if I'm eligible for weight loss injections like Mounjaro or Wegovy?
No — eligibility for prescription weight loss medication in the UK is based on BMI and health conditions, not BMR. Your GP or a licensed prescriber will assess your BMI and medical history. Use our GLP-1 weight loss calculator to explore potential outcomes, then discuss with your prescriber.
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.