The number of calories you need each day to maintain your current weight or to build muscle depends on your TDEE. TDEE is a combination of your basal metabolic rate (BMR) plus any extra physical activity or exercise you do.
TDEE is calculated using BMR, food thermogenesis (TEF), and exercise activity thermogenesis (EAT). The resulting estimate is close to your actual daily caloric needs.
BMR
BMR is the amount of energy that a person requires to maintain basic functions like breathing, pumping blood and producing hormones. It is one component of total daily energy expenditure (TDEE), which accounts for about 65 to 70 percent of a person’s total calories burned each day.
TDEE is calculated using a variety of factors, including BMR and activity level. It also takes into account the thermic effect of food and non-exercise activity thermogenesis (NEAT), which includes things like fidgeting, getting up and down from a chair or doing chores.
There are several different equations for calculating BMR, with the Harris-Benedict equation being one of the most popular. It takes into account height, weight, age and biological sex, as well as the average lean body mass of a person.
Another equation is the Mifflin St-Jeor formula, which uses the same variables but may be more accurate for people who are leaner than average. The Katch-McArdle formula, on the other hand, takes metabolic activity into account.
Thermic Effect of Food
The thermic effect of food (TEF) is the amount of energy your body burns in order to digest, absorb, and store the nutrients in food. TEF accounts for about 10% of your total daily energy expenditure.
It’s a vital factor in weight loss and maintaining your overall health. Eating a balanced diet and exercising regularly can help increase TEF and support your weight loss goals.
TEF differs from person to person, and can be influenced by factors like age, sex, body composition, and genetics. It’s also affected by meal variation, including frequency and size of meals.
Thermogenic foods, which burn more calories than they take to metabolize them, can boost TEF. Some high thermic foods include lean protein, fiber, and complex carbohydrates.
Thermic Effect of Activity
Thermic effect of activity (TEA) is calculated by adding together the calories burned from exercise and non-exercise activity thermogenesis, also known as NEAT. This includes things like walking the dog, taking the stairs to your office and shifting around in a chair at work.
The energy required for NEAT varies from person to person and can play a major or minor role in your total daily energy expenditure (TDEE). It can also vary from day to day depending on how active you are that day.
TEA accounts for about 15 to 30% of your total daily calorie burn. It also depends on how much you eat and what type of foods you eat. For example, protein has a higher thermic effect than carbohydrates or fats.
Non-Exercise Activity Thermogenesis
Your TDEE includes the energy that you burn at rest and when you’re moving around (basal metabolic rate or BMR). It also accounts for how much energy your body uses to digest, metabolize, and break down food.
In addition, it includes how much you burn during non-exercise activities such as typing at work, walking to the office, or mowing the lawn. These non-exercise activity thermogenesis calories add up, which can mean a significant difference in your total daily energy expenditure (TDEE).
Non-exercise activity thermogenesis plays a vital role in maintaining an optimal energy balance and contributing to weight maintenance. It is believed to be regulated by existing mechanisms that sense, accumulate, and integrate internal and external directionality signals with respect to energy intake and expenditure.