What is Basal Metabolic Rate?

If you were ever unsure of what ‘basal metabolic rate’ (BMR) meant and why it matters, you’re likely not alone.
 
BMR represents the number of kilojoules your body needs to perform its basic functions like breathing, circulating blood, and producing new cells, before you consider exercise and other physical activity.
 
Understanding your BMR is important because it forms the foundation of your daily energy needs and plays an important role in allowing you to maintain your healthy weight and overall health.
 
So, let’s take a look at some of the factors that affect BMR and how this knowledge can help guide you towards the healthiest version of you!

Resting metabolic rate (RMR) is the number of kilojoules your body needs to maintain your body’s basic functions like breathing and circulation, but unlike BMR, it does not require complete fasting or a specific rest period.
 
While BMR is measured under more stringent conditions (usually after 12 hours of fasting and eight hours of sleep), RMR is measured under less strict conditions and can be a slightly higher number due to the additional energy expended from processes like digestion.
 
Both RMR and BMR are important for understanding your body's energy needs, but RMR provides a more practical picture of your metabolic rate.

Understanding your BMR is important when it comes to maintaining a healthy weight, as it helps you tailor your energy intake to meet your energy expenditure goals.

Several factors influence BMR, including age (it typically decreases with age), sex (men usually have a higher BMR than women), weight, and muscle mass (more muscle mass increases BMR).

A normal BMR varies widely depending on individual characteristics.

Once you have your BMR, you can adjust your total energy intake based on your activity level to manage your weight and overall health effectively.
 
To calculate your BMR, you can use the Harris-Benedict formula, which takes into account your age, sex, weight, and height. This formula provides an estimate of the number of kiloujoules your body needs to function at rest. The Harris-Benedict equations are as follows:
 
For men: BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) - (5.677 × age in years)
 
For women: BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) - (4.330 × age in years)

Is it possible to change your BMR? The answer is both yes and no…
 
While some factors that influence BMR are beyond your control, such as genetics, others can be managed through lifestyle and dietary changes.
 
Genetics play a significant role in determining your BMR. Some people naturally have a higher or lower metabolic rate due to their genetic makeup.
 
Age is another factor – BMR tends to decrease as you get older. Sex also influences BMR, with men typically having a higher BMR than women due to a higher proportion of muscle mass. While you can't change your genetics, age, or sex, you can focus on lifestyle factors that impact BMR.
 
One of the most effective ways to boost your BMR is by increasing muscle mass through regular strength training exercises. Muscle tissue burns more energy at rest compared to fat tissue, so the more muscle you have, the higher your BMR will be.
 
Incorporating activities such as weightlifting, resistance band exercises, or bodyweight workouts can help build and maintain muscle mass.
 
The diet also plays a very important role in determining BMR. Eating enough protein is essential, as protein has a higher thermic effect on food (TEF) compared to fats and carbohydrates. This means your body burns more calories digesting protein-rich foods. Include lean meats, fish, eggs, legumes, and dairy in your diet to boost your protein intake.

Staying hydrated is important, as even mild dehydration can slow down your metabolism. Drinking plenty of water throughout the day can help keep your metabolic processes running smoothly.
 
Another tip to optimise BMR is to avoid extreme kilojoule restriction. While it might be tempting to drastically cut calories to fast-track your health goals, this can lower your BMR as your body enters a state of conservation. Instead, aim for a moderate energy deficit if you're trying to reduce your energy intake, ensuring you're still providing your body with the nutrients it needs.
 
Finally, get enough sleep. Poor sleep can negatively affect your metabolism and hormone levels, leading to a lower BMR. Aim for 7-9 hours of quality sleep per night to support a healthy metabolism.

Understanding your metabolic rate is essential when it comes to tailoring diet and exercise plans to your individual needs.
 
Factors like age, sex, weight, and muscle mass all play a role in influencing your BMR, and with the right lifestyle changes – such as incorporating strength training and a balanced diet – you can support a healthy metabolic rate.
 
For those seeking additional support, FBX's range of metabolism support supplements can be an excellent complement to your health journey. Explore our metabolism supplements.