TDEE Calculator

TDEE stands for total daily energy expenditure. It refers to the total number of calories your body burns in a day. 

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Online tools like a TDEE calculator give you a rough idea of your total daily energy expenditure TDEE by factoring in your basal metabolic rate BMR, physical activity, and thermic effect of food TEF.

In this article, we explain how TDEE calculators work by elaborating on the three TDEE variables. We also shed light on how knowing your TDEE helps you achieve your weight goal.

What is Total Daily Energy Expenditure?

When you digest food, it produces energy, which is measured in calories. This energy is then utilized to carry out vital functions and processes like respiration, blood circulation, renal filtration, cognitive activity, etc., as well as performing daily activities.

Total daily energy expenditure refers to the total energy (calories) your body consumes in a day. It is defined by three factors, namely, basal metabolic rate, activity level, and TEF.

While the first two variables are important determinants of TDEE, TEF is not that critical, and therefore, only considered in the most accurate TDEE calculator.

TDEE = BMR x Physical Activity Factor x TEF

It is essential to mention that a fourth factor called non exercise activity thermogenesis (NEAT) also affects the total daily energy expenditure. NEAT is the energy expended when you are not sleeping, eating, or doing a sports-like exercise.

The effect of NEAT on TDEE is minimal, and therefore, it is not included in TDEE calculations.

Before we get to the formulas used by a TDEE calculator, it is essential to have a clear understanding of three variables of total daily energy expenditure TDEE.

Basal Metabolic Rate BMR

Basal metabolic rate, or BMR represents the minimum number of calories you need for survival.

It is one of the most important defining elements of the total daily energy expenditure. In fact, in a healthy adult, BMR comprises almost 60% to 70% of TDEE.

Since metabolism varies under different circumstances, the lowest number of calories your body needs to perform vital functions like cell growth, respiration, blood circulation, etc., i.e., BMR, is calculated under three specific conditions.

These are:

  • The person should be in a complete state of rest, awake but physically inactive.
  • They should also not be anxious or excited, as the chemicals released in these states (cortisol for stress and dopamine for excitement) can alter metabolic rates.
  • Anyone taking BMR needs to be in an absolute fasting state for at least 6 to 12 hours, as the metabolic rate is higher than normal for a few hours after food intake.
  • They should also be in a neutrally temperate environment, i.e., 20°C to 25°C, as the metabolic rate fluctuates with weather.

Note that these optimal conditions for BMR ensure that the value obtained from the calculation is really the minimum energy requirement of the body.

This is where you need to know about resting metabolic rate RMR. While BMR and RMR are often confused, RMR is the total (not the lowest) number of calories your body uses up when at rest.

Factors Affecting Basal Metabolic Rate BMR

The following factors determine your basal metabolic rate:

Height and current weight (Body Mass)

Your weight and height compose your body surface. Understandably, people having higher body surfaces require more energy to function, and hence they would have higher BMR.

Gender

Gender plays an important role in body composition, and hence BMR differs for men and women.

Before we explain how sex factors in BMR (and total daily energy expenditure TDEE calculations), let’s first see how lean mass and body fat mass have different caloric requirements.

Muscles need the energy to contract and relax and, therefore, burn more calories than most body tissues. In fact, according to research, muscles consume almost 10 to 15 kcal/kg per day.

In contrast, body fat cells (adipose tissue) burn fewer calories than muscles.

Now, when it comes to body composition, men tend to have higher muscle mass (more lean body mass) and low fat body mass (as fat loss is rapid in them) than women and hence require more energy. This indicates a higher BMR and, by extension, higher total daily energy expenditure TDEE.

On the other hand, women have a high body fat percentage. This results in a slower metabolism than men and lowers BMR.

Age

Age is another important element of BMR and TDEE.

You might think that age shouldn’t affect BMR once an individual is fully developed in terms of height and weight (between the ages of 13 to 15 in girls and 12 to 16 in boys).

However, studies show a reduction in height, as well as an alteration in body composition, as the person grows old.

As we age, our linear bones shrink in size due to friction at joints. This friction results from the loss of protective, lubricating cartilage.

Typically, you lose almost one-half inch (1 cm) every ten years after hitting 40. Beyond the age of 70, this reduction in height becomes rapid, and you end up losing almost 1 to 3 inches with time.

Another important sign of aging is a significant decrease in lean mass and high body fat mass. This reduces BMR and TDEE.

Other Factors Affecting Metabolism

While BMR formulas only count age, gender, and body surface, there are some other factors that also affect metabolism.

Genetics

The exact science behind the relationship between genetics and metabolism is unknown. However, medical observation over the years suggests that variations in hereditary traits significantly impact your energy consumption.

Some people naturally have a high and efficient metabolic rate and, therefore, have a higher BMR and TDEE than others.

Weather

Weather and temperature are important components influencing the basal metabolic rate.

Our cells need an optimal, moderate temperature to maintain a stable intracellular environment, which is essential for normal bodily functions.

In extreme temperatures, the natural homeostatic mechanism sets in. This implies that the body self-regulates different features, like blood pressure, respiratory rate, etc., to keep the cells from potential damage.

This increases the basal metabolic rate and total daily energy expenditure.

Food Intake

Basal metabolic rate refers to energy consumption while your body is in an absolute fasting state. This is because the metabolic rate rapidly increases right after eating.

On the other hand, the body minimizes energy consumption during starvation, which means only the amount of calories absolutely vital for survival will be burned.

Drugs and Medications

Medicines have effects on metabolism. For example, medications that are taken to lose weight increase your metabolism to burn more fat.

Similarly, certain drugs, like caffeine, nicotine, cocaine, etc., also increase BMR.

Formulas Used For Basal Metabolic Rate BMR

There are three formulas used for basal metabolic rate; Revised Harris Benedict, Katch Mc. Ardle, and Mifflin St. Jeor equation.

Of all these, Mifflin St. Jeor formula is considered the most accurate.

Mifflin St. Jeor Equation

For Men:

BMR = (10 x weight in kg) + (6.25 x height in cm) – {(5 x age) + 5}

For Women:

BMR = (10 x weight in kg) + (6.25 x height in cm) – {(5 x age) – 161}

Harris Benedict Equation

Harris Benedict equation is the first BMR formula. It was later revised to give more accurate results.

For Men

BMR = (13.397 x weight in kg) + (4.799 x height in cm) – {(5.677 x age) + 88.362}

For Women

BMR = (9.247 x weight in kg) + (3.098 x height in cm) – {(4.33 x age) + 447.593}

Katch Mc Ardle Equation

BMR = 370 + {21.6 (1 – body fat percentage) x (weight in kg)}

Katch Mc Ardle is the only TDEE formula that considers body fat percentage. It is considered better than the Mifflin St Jeor equation in the case of healthy adults having high lean body mass.

Physical Activity

Physical activity is a crucial component of total daily calorie expenditure.

When you engage in physical exercises, your body understandably needs high amount of daily calories. This increases the total daily energy expenditure.

Work also increases muscle mass, which is another reason why TDEE is directly proportional to the level of physical activity.

Level Of Physical Activity

In some parts of nutrition, classification is simple, and you have low, high, or moderate activity.

However, for more accurate results, physical activity has been divided into the following five levels:

  • Light – exercise 1 to 3 times a week or sedentary lifestyle
  • Moderate – exercise 4 to 5 times a week
  • Active – daily exercise or intense exercise 3 to 4 times a week
  • Very Active – intense /heavy exercise 6 to 7 times a week
  • Extra Active – very intense exercise daily

In the above classification,

  • Exercise: 15 to 30 minutes of elevated heart rate
  • Intense /heavy exercise: 45 to 120 minutes of increased heart rate
  • Very intense: 2+ hours of increased heart rate

Physical Activity Factor

For TDEE calculation, physical activity levels have been assigned a constant number (ranges between 1.2 to 1.95).

This is called the activity factor and is frequently used in TDEE and calorie calculations.

Thermic Effect Of Food TEF

TEF is the amount of energy you need to initiate and continue metabolism.

It is generally estimated to be 10% of your total caloric intake. However, this largely varies for different kinds of foods.

TEF Of Different Macros

Macros are nutrients that constitute a large portion of your food. Proteins, carbohydrates, and fats are the macronutrients you consume in your daily diet.

Each of these food groups has different effects on metabolism. For example, proteins and carbohydrates are complex and, therefore, need more energy to break down.

Fats, on the other hand, are simpler in structure and, therefore, have a low TEF.

Here’s how much each of the macros increases your metabolic rate:

  • Proteins – 15% to 30% (highest TEF)
  • Carbs – 5% to 10%
  • Fats – 0% to 3%

Calculating TEF

The exact value of the TEF is difficult to measure. However, for use in the total daily energy expenditure calculator, it is estimated by multiplying the basal metabolic rate by 0.1.

TEF = BMR x 0.1

How Many Calories Do You Need In a Day?

Now that we are familiar with the total daily energy expenditure calculator, and its three variables, it’s time to discuss how you can use it to gain /lose weight.

However, before we get to that, it is essential to discuss our daily caloric needs for a healthy body weight.

While total daily energy expenditure TDEE and basal metabolic rate BMR are important factors in approximating your calorie requirement, you also need to take healthy body weight into account.

Ideal body weight is the healthiest weight associated with your age, gender, and height. The criteria for “healthiest” is simple – weight (body mass) that is linked to the lowest incidence of metabolic disorders and death is ideal for you.

There are several formulas to gauge healthy body weight. However, the most reliable and widely used is the body mass index range.

BMI is the ratio of your weight (in kg) and height (in cm2).

The BMI ratio is classified into the following four groups:

  • Underweight = <18.5
  • Normal = 18.5 to <25
  • Overweight = >25
  • Obese = 30 or higher

In healthy adults, weight to height ratio should ideally be in the healthy BMI range.

If your calorie intake places you in the underweight or obese category, you need to plan a diet keeping your total daily energy expenditure TDEE in mind.

Remember that the BMI scale has limitations and is not always accurate, as it does not factor in physical activity. For example, people who lift weights are active, and have a higher muscle mass, which often places them in overweight BMI category, even though they are perfectly healthy (and do not need to lose weight).

Also note that generally, the recommended daily calories for men and women is 2,500 and 2,000, respectively.

Using TDEE To Lose Weight

Most people use the TDEE calculator to lose weight.

Theoretically, you would need to consume fewer calories than your total daily energy expenditure, as this allows your body to burn fat reserves. Once you have estimated your TDEE and calorie requirement (through a calorie calculator), you can plan a meal accordingly.

However, instead of going all out with low-carb, low-fat, or very low-calorie diets to lose weight rapidly, we recommend considering the IIFYM diet plan to lose weight.

IIFYM, or If It Fits Your Macros, is a popular weight loss strategy that believes you can eat anything you like as long as it fits your macros. In an IIFYM plan, you calculate macros instead of entirely eliminating certain foods from your weight loss diet.

Apart from weight loss, this strategy also helps maintain the weight change.

Here’s how the three macros contribute to your total calories:

  • 1 gm of protein = 4 calories
  • 1 gm of carbs = 4 calories
  • 1 gm of fats = 9 calories

Clearly, fats burn more calories than the other two macros. To add to this, excess fat is stored in the body as an energy reserve and is the main reason you gain weight.

At the same time, certain types of carbs like cellulose do not digest in the body and hence do not add to the calorie count. However, they stay in the GIT and keep you feeling full for a long time. This helps in weight loss.

The same applies to proteins. Generally, people who want to lose weight go big on a protein-rich diet while completely restricting carb and fat intake. This is because proteins increase metabolic rate and also help in fat loss.

All-in-all, tracking your macros via a macro calculator enables you to lose weight and (sustain the weight loss), without having to compromise on your favorite food.

TDEE To Gain Weight

If you want to gain weight, your calorie intake should understandably be higher than your TDEE.

When it comes to healthy weight gain, you aim to increase your lean body mass (total weight minus the weight from body fat), as a high body fat is associated with several metabolic diseases.

Research shows that a good target for an increase in lean muscle mass is achieved when your calorie intake is 110% of your TDEE.

Keeping this in mind, plan your meal. To ensure you gain weight without risking health complications, make sure your diet is rich in organic, natural calories, primarily sourced from proteins and carbs.