Total Daily Energy Expenditure (TDEE) Explained
Let’s take a minute to discuss total daily energy expenditure. It’s very helpful from a nutritional and overall health standpoint to understand this term and the different variables in this equation. A deeper understanding of the meaning of this term will help you better understand your bodies metabolism.
Total daily energy expenditure (TDEE ) refers to the total number or net calories you burn in a day. As you can imagine, this varies wildly from person to person depending on their genetics, body physique, level of activity and diet. For those interested, this field of study is often referred to as bioenergetics and follows some basic principles of biochemistry and physics .
At it’s most basic description, it describes energy output. Output is defined as the number of calories you expend in a given day. In other words, what we burn. Note that total daily energy expenditure does not account for caloric intake, only for calories burned.
TDEE can actually be broken down into several components that can better explain it’s meaning. The first is resting energy expenditure. Resting energy expenditure is the amount of energy it takes us to stay alive without any level of physical activity. It describes the key functions of our body, such as making our heart pump or the neurons in our brain to fire. This is makes up about 70% of your body's daily energy expenditure.
The second term is the thermic effect of food. This describes the energy required to process and digest food. Imagine that the food you eat is not instantaneously converted to “energy” that the body can use. Part of your metabolism is converting this food into energy the body can utilize. This is about 10% of your body's daily energy expenditure.
These two processes, resting energy expenditure and thermic effect of food, can essentially be combined into a term called basic metabolic rate. Technically, these are separate terms, however combining them simplifies what you have to remember. BMR is a term you will see used more often because it’s simpler to use and remember. Just remember that BMR is describing the energy your body uses at rest throughout the day and we’re just including the energy it takes to convert food and drink into energy.
The final component is called activity energy expenditure. This is a fancy way to describe the amount of energy you burn each day doing physical activity. This definition can include low energy activities such as walking through a mall, or more intense things such as working out or playing sports. This number can vary wildly from 0% in sedentary folks for up to 30% in very active folks.
You can calculate your TDEE using an online calculator, and there are many. Just google total daily energy expenditure. There are multiple models or equations used to calculate TDEE, for example the harris-benedict equation. I’ve not seen any validated studies that suggest one particular model is a more accurate predictor of TDEE. As your height or weight increase, so does your TDEE goes up. As your age increases, TDEE goes down.
So, in summary. TDEE = REE + TEF + AEE. This can be further simplified to TDEE = BMR + AEE. The calculator for TDEE can help you estimate how many calories you need to eat to have a positive or negative calorie balance or to maintain your calorie balance.