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BMR: What Is My Basal Metabolic Rate?

BMR: What Is My Basal Metabolic Rate?
Claire Muszalski
Writer and expert3 years ago
View Claire Muszalski's profile

If you've been in the fitness space for a while you've probably asked yourself, what is BMR? BMR, or basal metabolic rate, is the number of calories your body needs to accomplish its basal (most basic) life-sustaining functions.

To give it its full scientific description, basal metabolic rate (BMR) is the amount of energy expended while at rest in a neutrally temperate environment. In simpler terms, the number of calories you require over a 24-hour period without the inclusion of movement of any kind or through the digestion of food. 

If you’ve ever wondered what BMR accounts for, it’s the energy required to maintain vital organs such as the liver, brain, heart, lungs, kidneys as well as muscle mass and skin. Around 70% of the overall calories you require are burnt purely for the above basal processes. Another 10% are used for maintaining body temperature and digesting food. That means only 20% of the calories we require overall are burnt during movement. 

If you were to lay in bed all day and not move a muscle, you would still need to consume around 80% of your overall calories to keep your body running properly. BMR varies between individuals and a study of 150 adults in Scotland reported an average BMR of 1500 calories a day, with the lowest being 1027 calories per day and the highest being 2499 calories per day.1 

Summary: Your BMR is the number of calories your body burns at rest.

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How to calculate your BMR

BMR is dependent on factors such as age, height, weight, sex and lean muscle mass. You can calculate your BMR here.

To calculate your BMR, you can use the following formula:

Females: 10 * weight (kg) + 6.26 * height (cm) – 5 * age (years) – 161  Males: 10 * weight (kg) + 6.26* height (cm) – 5* age (years) + 5 

Why you might want to know your BMR

If you’re trying to lose, gain, or maintain weight, knowing your BMR helps you to determine how many calories you need each day.  

To lose weight

Losing weight means you need to burn more calories than you’re taking in. Start with your BMR and use these equations to help calculate your calorie burn to adjust your calorie intake (diet). 

To maintain weight

Keeping your weight the same can also be done by knowing your BMR and an estimate of how many calories you burn through exercise. Eating the same number of calories that you burn helps maintain weight. 

To gain weight

If you want to gain weight, you need to consistently consume more calories (through food) than you’re burning (based on your BMR and exercise). Eating about 500 extra calories per day (over your BMR + exercise) can help you gain about 1 pound per week.

Can I eat fewer calories than my BMR?

Chronically eating fewer less calories than your BMR can be very detrimental to your health. Low energy availability can lead to disordered eating, fatigue, hair loss, increased healing time from injuries, reduced bone density (meaning increased likelihood of fractures), and low mood. Chronic low energy availability also affects hormone production and can lessen the production of key hormones like testosterone.2 

On top of these health risks, if you eat below your BMR for an extended period of time, your body’s metabolism will start to slow down.2 This will make it harder for you to lose weight long term and ultimately stall progressive changes in body composition.  

Summary: It’s best to not eat below your BMR calorie level for an extended period of time.

How do I set my calories?

Remember, on a simple level, it’s all about calories in, calories out. 

As individuals we all have our own calorie requirement to maintain our current weight, not just at a BMR level but also depending on how many calories we expend through exercise and day-to-day movement.

1. Calculate your BMR 

So, setting your calories will depend on what your exercise level is, as well as your BMR, and what your goals are too.

2. Determine your calories burned through exercise 

If your primary goal is muscle growth or fat loss, focus should be placed on increasing overall muscle mass. The more muscle mass we have, the higher our calorie requirements, which naturally leads to an increase in fat loss.1

3. Add or subtract calories in your diet based on your goals 

If you’re serious about getting results, you ought to be predominately lifting weights through big progressive movements such as squats, deadlifts, presses etc., whilst also feeding your body correctly, taking note of your own specific BMR and overall calorie needs. 

Upping your steps and cardio activity is also a key element when you’re trying to lose weight, to increase your calorie deficit. Adding more calories and protein is key for gaining muscle. 

After reading this article, you should realise that blindly cutting calories too excessively will have consequences, as mentioned above. So, always try to find what’s right for you, and consult your GP first. 

If you’re looking to learn more about calculating the right calorie deficit for you, use the article below. 

Summary: To calculate your calorie needs, you need to know your BMR and add or subtract calories based on your workouts and your goals.

Take home message

Our bodies are designed to be fuelled, not starved. Chronically undereating will not get you long term results and can lead to a number of dangerous health risks. Understanding your basal metabolic rate and overall calorie requirement will help you get one step closer to your goal body.

Interested in more expert nutrition advice?


Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you're concerned, consult a health professional before taking dietary supplements or introducing any major changes to your diet.

1. Alexandra M Johnstone, Sandra D Murison, Jackie S Duncan, Kellie A Rance, John R Speakman, “Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine”, The American Journal of Clinical Nutrition, Volume 82, Issue 5, November 2005, Pages 941–948

2. Mathisen TF, Heia J,Raustøl M, Sandeggen M, Fjellestad I, Sundgot-Borgen J. “Physical health and symptoms of relative energy deficiency in female fitness athletes.” Scand J Med Sci Sports. 2020;30(1):135-147. doi:10.1111/sms.13568 

Claire Muszalski
Writer and expert
View Claire Muszalski's profile

Claire is a Registered Dietitian through the Academy of Nutrition and Dietetics and a board-certified Health and Wellness Coach through the International Consortium for Health and Wellness Coaching. She has a Bachelor of Science in Biology and a Master’s degree in Clinical Dietetics and Nutrition from the University of Pittsburgh.

Talking and writing about food and fitness is at the heart of Claire’s ethos as she loves to use her experience to help others meet their health and wellness goals.

Claire is also a certified indoor cycling instructor and loves the mental and physical boost she gets from regular runs and yoga classes. When she’s not keeping fit herself, she’s cheering on her hometown’s sports teams in Pittsburgh, or cooking for her family in the kitchen.

Find out more about Claire’s experience here.