TDEE or total daily energy expenditure isn’t too complex to understand. You see, for us to have the energy to do essentially anything, our bodies have to use the calories that we consume as a fuel source. 

Therefore, we’re “expending” energy. And this is similar to how a car needs gas to drive. You supply the fuel, it uses the fuel to keep going. 

But what factors are involved in the process of TDEE?

There are many factors that determine how many total calories you burn every day include…

• Gender 
• Age
• Weight
• Height
• Activity levels
• Body composition
• Nutrition 
• Genetics
• Body temperature

However, the calculator or formula only considers gender, age, weight, height, and activity levels. So, let’s break down each one a little further so you can understand how each contributes to TDEE.

Gender

Men and women tend to burn calories at a different rate with men usually burning more overall and that’s because of the male hormones that allow men to have more muscle with less fat biologically. 

Women also need more fat for reproduction and the menstrual cycle. 

Age

As we get older, the metabolism naturally starts to slow down. But the likely main cause for this is because skeletal muscle uses up the most energy in the body. And we know that muscle loss is associated with aging.

Fat gain is also common as well which affects metabolic rate.

According to a scientific review, “It is shown that the decrease in muscle mass relative to total body may be wholly responsible for the age-related decreases in basal metabolic rate”. (1)

Weight 

Heavier individuals generally have a higher basal metabolic rate compared to lighter individuals. 

Height

Taller people tend to have more lean body mass overall due to the additional body surface area compared to a shorter individual.

Activity levels

Non-exercise activities and intentional exercise both burn calories although the latter obviously burns much more in the same period of time. Not to mention, exercisers usually benefit from excess post-exercise oxygen consumption (EPOC) which allows the body to burn additional calories for several hours following activity.

How to calculate TDEE using the formula

To calculate TDEE, you’ll need to first know the formula that makes this possible. There are several formulas that are used, However,  according to research, the Mifflin-St Jeor seems to be the most accurate. (2)

Here’s the Mifflin-St Jeor formula…

Men: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) + 5 

Women: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) – 161

So let’s do one example of how an individual could determine their TDEE with the formula. We’ll use a 25-year-old male who is 177cm/5’10 and weighs 72kg/160 lbs. You’ll also notice the formula uses the metric system.

So you’ll basically plug the male’s stats into the formula like so… 10 x weight (72) + 6.25 x height (177) – 5 x age (y) + 5 

This equates to 1,706 calories as your basal metabolic rate to support basic life functions.

Then based on your level of physical activity every day, this number obviously increases as your energy requirements will change.

Now, to calculate your TDEE, you’ll take your basal metabolic rate and multiply it by the activity factor formulas below… (3)

• Sedentary — desk job and little to no exercise (multiply by 1.2)
• Lightly Active — light exercise/sports 1–3 days/week (multiply by 1.375)
• Moderately Active — moderate exercise/sports 3–5 days/week (multiply by 1.55)
• Very Active — hard exercise/sports 6–7 days/week (multiply by 1.725)
• Extremely Active — hard daily exercise/sports and physical job or training (multiply by 1.9) 

And it’s really just that simple (or at least we hope it was)! 

The calculator provides optimal nutritional information based on your goals. Plus, it’ll give you some very handy additional information as well. 

This includes an estimate of your ideal weight, your BMI (body mass index), an estimate of your maximum muscular potential, and calorie/macronutrient requirements to reach your goals!