What is BMR?
BMR stands for “Basal Metabolic Rate”. Basal metabolic rate is defined as the number of calories burned by your body for its life-sustaining activities.
Life-sustaining activities include breathing, pumping of the heart (blood circulation), digestion of food, removal of impurities from the body, etc.
These activities occur daily and the energy required by them is almost constant. The BMR varies from person to person depending on things like their age, weight, height, gender, and lean mass.
Lean mass is the amount of muscle a person has. Lean mass requires a lot of energy to maintain, hence its effect on BMR is significant. Males usually have higher BMR due to having a higher lean mass.
What is TDEE?
TDEE stands for “Total Daily Energy Expenditure”. TDEE is the measurement of how many calories have been burned in a single day by accounting for all the activities that a person has done on that day.
BMR is also included in the measurement of TDEE. BMR is constant over long stretches of time but TDEE can vary from day to day.
The TDEE of a person who is very active and exercises regularly will be way higher than the TDEE of a person who has a sedentary lifestyle.
A sedentary lifestyle means that a person has little to no physical activity in their life. Having a desk job and not doing any gym or sports is a prime example of a sedentary lifestyle.
Difference between TDEE and BMR
The main differences between TDEE and BMR are listed below:
- BMR is constant while TDEE is different every day.
- BMR does not account for physical activity in the energy expenditure while TDEE does.
- TDEE is the parameter that is more important during weight loss/gain routines while BMR is comparatively less important.
These were the main difference between BMR and TDEE.
How to calculate TDEE and BMR
The most accurate method to calculate TDEE and BMR is to get a professional lab test. This test is called a “Calorimetry test” and it measures how much energy you use by measuring your oxygen intake and carbon dioxide output.
However, lab tests can be expensive and time-consuming. So, people who either cannot afford the test or need a quick result can use some equations that can help them to estimate their BMR and TDEE.
It must be noted that the results of these equations are not as accurate as a lab test and should not be used for medical reasons.
Mostly only people who are doing a dieting course will find a use for these methods of calculations. Some of the most popular equations are discussed further.
Equations for Calculating BMR
There are many equations for calculating BMR. According to this study, there are as many as 248 equations that are used to calculate BMR. Each equation uses different properties of your body such as hip-to-waist ratio, body mass index, gender, race, etc. However, we will only discuss a few of the most well-known equations.
- Harris-Benedict equation. This equation was originally devised in 1918 by James Arthur Harris and Francis Benedict. It was revised in 1984 to increase its accuracy.
The revised equation is as follows:
Men BMR = 88.362 + (13.397 * weight in kg) + (2.799 * height in cm) – (5.677 * age in years)
Women BMR = 447.593 + (9.247 * weight in kg) + (3.098 * height in cm) – (4.440 * age in years)
- Mifflin-ST Jeor Equation. This equation was another revision to the Harris-Benedict equation in 1990. It is widely considered to be superior to the previous equation.
The equation is as follows:
Men BMR = (10 * weight in kg) + (6.25 * height in cm) – (5 * age in years) + 5
Women BMR = (10 * weight in kg) + (6.25 * height in cm) – (5 * age in years) – 161
- Katch-McArdle equation. This equation requires you to know your body fat percentage. It is used by people who have a higher lean mass than average as it is more accurate for them.
The equation is:
BMR = 370 + (21.6 * lean body mass)
Lean body mass is calculated by multiplying body weight with fat percentage.
These are some of the most used equations to calculate the “Basal Metabolic Rate”.
Equations for Calculating TDEE
The TDEE calculation is not very precise. At best, it can be called an estimate. It is simple to calculate if you already know your BMR. Depending on how active you are, you just have to multiply your BMR with one of the following numbers:
- TDEE = BMR * 1.2; applicable to a sedentary lifestyle (no exercise).
- TDEE = BMR * 1.3; applicable to those who do light exercise from once to three times a week.
- TDEE = BMR * 1.55; applicable to those who do moderate exercise 3-5 times a week.
- TDEE = BMR * 1.725; applicable to those who do hard exercise 6-7 days a week.
- TDEE = BMR * 1.9; applicable to those who do hard exercise every day and/or have a highly demanding physical job (e.g., construction work).
Additionally, you can use an online tool such as a TDEE calculator to calculate your TDEE for you. You would need to provide the tool with your age, height, gender, and weight. The rest, the tool will do itself and give you the results.
And there you have it, the differences between “Total Daily Energy Expenditure” and “Basal Metabolic Rate”.
In simple terms, we can define BMR as the energy expended by your body to keep you alive, while TDEE is your BMR plus any energy you use in physical activities such as running, lifting weights, etc.
Accurate results of BMR and TDEE can only be calculated using a lab test. However, for those who want the answers faster than a lab test, they can calculate them using a number of different equations that we discussed above.