TDEE Calculator

Use this TDEE calculator to determine the calories your body burns daily. It's suitable for all age groups, including young children. The calculator incorporates the most recent formulas developed by the Institute of Medicine of the National Academies, as detailed in their Dietary Reference Intakes (DRI) report.

What is TDEE?

TDEE, or Total Daily Energy Expenditure, is the energy your body uses daily and also a measure of the calories required to sustain your current weight. Consuming fewer calories than your TDEE will decrease weight while consuming more than your TDEE will cause weight gain.

Your body utilizes energy to maintain its autonomic functions, including breathing, the nervous system, blood flow, body temperature regulation, and physical movements. Energy is also necessary for transporting, synthesizing, and replenishing molecules that form body tissues. The body obtains the necessary energy by breaking down chemical bonds in the food you consume through oxidation.

The three essential nutrients that provide your body energy through food are carbohydrates, protein, and fat. Carbohydrates and proteins release approximately 4 kcal per gram, whereas fat releases around 9 kcal per gram.

Components of Your Body's Energy Expenditure

Basal Metabolic Rate (BMR)

Basal metabolic rate (BMR) represents the energy used by your body for essential metabolic functions without being affected by food digestion or physical activity. It reflects the minimum amount of energy needed to sustain your life. An accurate BMR measurement requires a specific environment, such as an overnight fast of 12 to 14 hours, where the individual rests on their back at a neutral temperature. BMR is typically extrapolated over 24 hours, known as basal energy expenditure (BEE), and is expressed as kcal per day.

Obtaining the necessary tools for measuring BMR may not always be readily accessible. Nonetheless, BMR and BEE can be approximated using prediction equations based on physical characteristics like weight, height, gender, and age. The size of the body is closely linked to BMR, with the most significant correlation being lean body mass, which is the body's overall weight, excluding its fat mass. Research suggests that lean body mass plays a vital role in determining BMR, making up approximately 73% of one's BMR, while fat mass only contributes an additional 2%.

Thermic Effect of Food (TEF)

The Thermic Effect of Food, or TEF, is the metabolic rate increase after consuming food. It includes the energy used for the digestion, absorption, transportation, metabolism, and storage of ingested nutrients. The amount and composition of the consumed food impact TEF, with fats requiring the least energy to be processed, followed by carbs and protein. On average, consuming a balanced mix of macronutrients results in an additional energy expenditure of approximately 10% of the consumed energy.

Thermic Effect of Physical Activity (TEPA)

The amount of energy used for physical activity is the most diverse factor in the body's overall energy usage. It varies greatly among individuals. The Thermic Effect of Physical Activity typically makes up 15 to 30% of daily calorie expenditure. However, it can increase to 50% or more for those who are regularly active, engage in intense physical labor, or participate in sports. This includes energy expended during structured exercises and non-exercise activities, known as non-exercise activity thermogenesis (NEAT). NEAT encompasses the energy used for everyday tasks such as household chores, walking to the bus, light movement while sitting, driving, shopping, and fidgeting.

TDEE and Weight Management

Total daily energy expenditure (TDEE) consists of three components:

1. The basal energy expenditure (BEE)
2. The thermic effect of food (TEF)
3. The thermic effect of physical activity (TEPA)

If the amount of calories you consume and digest matches the number of calories you expend (your TDEE), your body will stay at its current weight. However, if you consume more than your TDEE, the excess calories will be stored as fat in your fat tissues, causing weight gain. On the other hand, if you consume less than your TDEE, your body will use stored fat for the extra energy it needs, resulting in weight loss.

Measuring and Calculating Energy Expenditure

There are several internet-based tools available to calculate TDEE. These tools use predictive algorithms to determine BMR, RMR, or REE. They then apply a multiplier based on your physical activity level to determine your TDEE value.

Various prediction equations are commonly used to estimate a person's metabolic rate, including BMR, RMR, and REE, based on height, weight, sex, and age. Some of the most well-known equations include the updated Harris-Benedict formula, the Mifflin St-Jeor equation, and the Katch-McArdle formulas, all developed by analyzing energy expenditure data from individuals in the general population. These data are typically obtained through indirect calorimetry measurements performed in controlled laboratory settings, which involve measuring a person's oxygen consumption and carbon dioxide production to determine their energy expenditure.

This calculator, instead, utilizes the latest predictive formulas developed by the Institute of Medicine of the National Academies. Their formulas were based on data from energy expenditure studies using Doubly Labelled Water (DWL). The measurements were conducted on a total of 767 adults (ages 19 and over), 844 children (ages 3 to 18), and 320 infants and children (up to 2 years old).

DLW measurements are now considered the most reliable method for determining TDEE. This is due to their ability to accurately measure energy spent by individuals in their natural, non-restricted daily routines. Unlike indirect calorimetry, DLW studies track energy expenditure in real-life scenarios without the limitations of a controlled laboratory setting.

The DLW method entails providing individuals with two stable isotopic forms of water and tracking the rate at which they vanish from bodily fluids (such as urine or blood) throughout 1 to 3 weeks. The differences in the disappearance rate indicate the level of carbon dioxide production. From the disappearance rate and the knowledge of the diet composition, TDEE can be accurately determined.

Estimated Energy Requirement (EER)

According to the Dietary Reference Intakes report, the Estimated Energy Requirement (EER) is the calories needed to sustain overall well-being. Thus, this calculator computes and presents energy usage based on EER, not TDEE, for individuals with an average weight. The EER prediction formulas apply to:

1. Adults who are considered to have a healthy weight based on their BMI (Body Mass Index) falling between 18.5 and 25.
2. Children between the ages of 3 and 18 who fall within the 5th and 85th percentile for BMI.
3. Infants and toddlers aged up to 2 years who fall within the 3rd and 97th percentile for BMI.

Individuals who are overweight and aiming to lose weight can refer to their TDEE value, calculated using the DRI formulas in this calculator. This value can serve as a guide when setting a realistic weight loss goal. To reach a lower, stable body weight, overweight individuals should consume fewer calories than their current TDEE. A recommended starting point would be to consume 200 fewer calories per day than their TDEE. It is important to note that as weight is lost, TDEE will also decrease. Therefore, regular check-ins on TDEE throughout the weight loss journey are crucial to ensure that calorie intake remains below TDEE.

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