When we speak about calories out we refer to metabolism and activity burn.
The first component of energy expenditure that is BMR.
BMR is also termed as your basal metabolic rate.
It is the amount of energy expressed in calories that a person needs to keep the body functioning at rest.
Just imagine lying down on a sofa the whole day doing nothing at all.
Well, this is just a hypothetical situation where your body is burning calories to sustain life.
That is, you know, beating of your heart energy for your brain, breathing, essentially maintaining
homeostasis. Now, BMR accounts for about 50 to 70 percent of daily energy expenditure calories out. There are more formulas to calcolate your BMR the most popular are the Katch MacArdle equation and Mifflin’s equation. On the web you can find many calculator. Try this one https://www.calculator.net/bmr-calculator.html
An empirical way to estimate it, is to multiply your weight in pound for 10, if you have your weight in KG, multiply it for 2.2 and you have your weight in pound. For example you are 70 KG that is 154 pound, ten times is 1540. This is your BMR.
You basale metabolism need to be corrected with your life style, or better any activity we carry out require energy this we call thermic effect of activity and can be calculated with a multiplier:
Sedentary = BMR X 0.2 (little or no exercise, desk job)
Lightly active = BMR X 0.375 (light exercise/sports 1-3 days/wk)
Mod. active = BMR X 0.55 (moderate exercise/sports 3-5 days/wk)
Very active = BMR X 0.725 (hard exercise/sports 6-7 days/wk)
Extra active = BMR X 0.9 (hard daily exercise/sports & physical job or 2X day training, i.e marathon, contest etc.)
In the example above Johnny is 70 kg and has a moderate activity so BMR 1540 x 0.55= 847. The TEA of Johnny is 847 calories.
Now let’s discuss the second component of energy expenditure that is thermic effect of food TEF.
The thermic effect of food is the caloric cost of digesting and processing different macronutrients in your diet.
-Protein: 20-35% of calories burned through processing -Carbohydrates: 5-15% of calories burned through processing -Fats: 0-5% of calories burned through processing
To put this in tangible terms, if you eat 200 calories worth of protein, your body will use between 40 and 70 of them indigestion. The most common estimate for the total thermic effect of food is around 10 percent of your total BMR in our example BMR 1540 the TEF is 154 calories.
Ok now we can put all together and see how is the balance of calories for Johnny or TDEE , Total Daily Energy Expenditure
His weight is 154 pound his BMR 1540, the TEF 154 calories and with is moderate activity more 847 calories.
If Johnny eats these many calories every day, he will maintain his weight.If he eats less than 2541 calories, he will lose his weight.
And if he goes into caloric surplus, if that is, if he eats more than 2541 calories, he will gain weight.