## What is Total Daily Energy Expenditure (TDEE)

**Total Daily Energy Expenditure** (TDEE) means the total number of **calories** used by a **person in a day**.

This energy consumption represents three significant energy outlets:

**Basal Metabolic Rate (BMR)****Thermic Effect of Food (TEF)****Physical Activity Level (PAL)**.

In a simple formula, this equates to: **BMR** + **TEF** + **PAL** = **TDEE**.

TDEE is a useful metric for individuals seeking to maintain, gain, or lose weight. TDEE is also widely utilized by the body building community. Understanding your TDEE allows for the tailoring of nutritional intake and exercise routines to meet specific weight management or body building goals.

Read more about TDEE here

## Online TDEE Calculator

An online TDEE calculator is a digital tool designed to provide an estimate of an individual’s total daily energy expenditure based on their specific inputs such as age, sex, weight, height, and level of physical activity.

It is important to treat all results from an TDEE calculator as an estimate. Also consider the error rates of the formula used, see below here for more about error rates.

## How to Use a TDEE Calculator

Enter the required information: age, sex, height, weight, and physical activity level. The calculator will then use this data to estimate your TDEE.

The level of physical activity is usually categorized as sedentary, lightly active, moderately active, very active, or extremely active. Ensure you make a realistic and honest selection to achieve an accurate TDEE estimation.

## Alternatives to TDEE Calculators

While online TDEE calculators are beneficial and helpful, they operate on formula that offer an approximation. There are more precise and alternative measurements available. Formula calculations can also be used in conjunction with or as an aid to the below alternate tests.

#### Other alternatives include:

**Laboratory Tests:**Lab tests can measure Resting Energy Expenditure (REE), and you can add an estimate of energy expenditure from physical activity and the thermic effect of food.**Wearable Devices:**Wearable devices such as fitness trackers and smartwatches can estimate daily calorie expenditure by tracking heart rate and movement.**Metabolic Rate Testing Devices:**These devices measure the oxygen you breathe out to determine the number of calories you burn at rest.**Doubly Labeled Water Test:**This involves drinking water heavy in hydrogen and oxygen to derive the carbon dioxide production.

### Laboratory Tests:

The most accurate laboratory test to measure REE is indirect calorimetry. During an indirect calorimetry test, a person’s oxygen consumption and carbon dioxide production are measured. The body uses oxygen to metabolize nutrients and create energy, while the carbon dioxide produced is a byproduct of this process. By analyzing the ratio of oxygen used to carbon dioxide produced, scientists can estimate the number of calories a person burns at rest.

TDEE is then calculated from REE by adding the two additional energy expenses, thermic effect of food and physical activity.

### Wearable Devices:

Wearable devices, such as fitness trackers and smartwatches utilize a combination of sensor data and algorithms to estimate energy expenditure.

These devices typically track motion and heart rate. Accelerometers and gyroscopes inside the device measure the number, intensity, and frequency of a person’s movements. The optical heart rate sensors built into the wearable measure changes in blood flow to estimate heart rate.

The wearable and its application then combines all the data available with your personal body metrics to estimate the about of calories you burn each day.

### Metabolic Rate Testing Devices:

Metabolic rate testing devices are specialized machines that measure your metabolic rate or the number of calories your body burns in a day. One such device is a resting metabolic rate (RMR) tester, which determines your RMR based on the oxygen you consume.

These devices utilize the indirect calorimetry method but are typically more portable. During the test, you are required to sit quietly, relax, and breathe into a mouthpiece. The device measures the amount of oxygen you breathe out and uses this data to calculate the number of calories you burn at rest.

### Doubly Labeled Water:

Doubly labeled water and indirect calorimetry are the gold standard for human energy requirement or TDEE and are routinely used in clinical studies. Doubly labeled water involves drinking water labeled with stable isotopes of hydrogen and oxygen and then collecting urine samples over a specified period to measure isotope elimination. Energy expenditure is derived from the measurement of carbon dioxide production.

This test can be very expensive and time consuming. The turnover rates of the hydrogen and oxygen of body water is assessed from blood, saliva, or urine samples, collected at the start and end of the observation interval of 1–3 weeks. Each test per person is around $1500 and takes anywhere from 7 to 15 days to complete.

**Understanding How TDEE Calculators Work**

TDEE calculators operate on established formula, the most common being the **Mifflin-St. Jeor equation**:

For men:

TDEE = 10 * weight(kg) + 6.25 * height(cm) – 5 * age(y) + 5

For women:

TDEE = 10 * weight(kg) + 6.25 * height(cm) – 5 * age(y) – 161

These equations first calculate the BMR. The result is then multiplied by an activity factor (varying from 1.2 to 2.5) to account for physical activity, resulting in the TDEE.

Some studies suggest an error rate of up to 10% for the Mifflin-St Jeor Equation. Which is one the lowest out of the resting metabolic rate formula. If you have an accurate estimate of your body fat percentage the Katch-McArdle equation is often considered to be slightly more accurate.

## Find your TDEE Manually without a Calculator

To calculate your TDEE yourself, you first need to determine your basal metabolic rate, or BMR, which is the amount of energy your body uses at rest. Once you have your BMR, you can then approximate your total daily energy expenditure by identifying your activity level multiplier. Several equations have been devised to estimate BMR, and below are some of the most popular and widely recognized BMR estimation formulas.

#### 1. Pick an equation to find your BMR

**Harris-Benedict Equation:***For Men:* BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) − (5.677 × age in years) *For Women:* BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) − (4.330 × age in years)

**Mifflin-St Jeor Equation:***For Men:* BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5*For Women:* BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161

**McArdle (Katch-McArdle) Equation: **If you have an accurate body fat estimate.

BMR = 370 + (21.6 × LBM in kg)

**Schofield Equation:** **Males Aged 0-3**: BMR=(59.512×weight in kg)−30.4**Males Aged 3-10**: BMR=(22.706×weight in kg)+504.3**Males Aged 10-18**: BMR=(17.686×weight in kg)+651.7**Males Aged 18-30**: BMR=(15.057×weight in kg)+692.2**Males Aged 30-60**: BMR=(11.472×weight in kg)+873.1**Males Aged 60+**: BMR=(11.711×weight in kg)+587.7

**Women**:**Females Aged 0-3**: BMR=(56.706×weight in kg)−54.6**Females Aged 3-10**: BMR=(22.512×weight in kg)+505.0**Females Aged 10-18**: BMR=(13.384×weight in kg)+692.6**Females Aged 18-30**: BMR=(14.818×weight in kg)+486.6**Females Aged 30-60**: BMR=(8.126×weight in kg)+845.6**Females Aged 60+**: BMR=(9.082×weight in kg)+658.5

**Cunningham Equation:** Lean Body Mass (LBM) to calculate BMR.

BMR = 500 + (22 × LBM in kg)

**Kleiber’s Law:** Originally for animals and is based on body mass.

BMR = body weight in kg 0.75 × 70

**Owen’s Equation:***For Men:* BMR = 879 + (10.2 × weight in kg)*For Women:* BMR = 795 + (7.18 × weight in kg)

**Livingstone’s Equation:** *Men:* BMR = 293 − (3.8 × age) + (456.4 × height in meters) + (10.12 × weight in kg)*Women:* BMR = 448 − (3.9 × age) + (401.5 × height in meters) + (8.6 × weight in kg)

#### 2. Pick your daily average activity level

Once you have the BMR from any of the above equations, you can calculate your TDEE by multiplying your BMR by an activity factor, which represents your level of physical activity:

**Sedentary (little or no exercise)**: BMR x 1.2**Lightly active (light exercise/sports 1-3 days/week)**: BMR x 1.375**Moderately active (moderate exercise/sports 3-5 days/week)**: BMR x 1.55**Very active (hard exercise/sports 6-7 days a week)**: BMR x 1.725**Super active (very hard exercise/sports & physical job or 2x training)**: BMR x 1.9

The resulting number is the amount of calories you require each day while taking in account your activity level.

**Why Use an Online TDEE Calculator**

**Ease of Use:**Inputting a few key data metrics, anyone can very quickly and simply receive an estimate of their daily caloric needs.**Accessibility:**Online TDEE calculators are widely available and can be accessed at any time, from anywhere, without any cost.**Individualization:**TDEE calculators offer a personalized estimate based on your specific details like age, height, weight, and activity level, leading to more accurate results than general guidelines.**Helps in Goal Setting:**Your TDEE can provide a solid foundation for your nutritional and exercise planning whether you are trying to lose, maintain, or gain weight. It’s a good base to start from knowing how many calories you require each day.

**Disadvantages of Using a TDEE Calculator**

**Accuracy:**The accuracy of TDEE calculators is reliant on the information entered.**Activity Level:**The activity level parameter is hugely subjective and can be hard to interpret. Activity levels can also vary from day to day. So it is recommended to find an average.**Generalized Formula:**TDEE calculators are based on average population data. Individual variations in metabolism aren’t accounted for, which could lead to inaccurate results for some people.**Does not Account for Body Composition:**Most TDEE equations cannot differentiate between lean mass and fat mass. People with a higher muscle mass may burn more calories even at rest, potentially leading to underestimations of TDEE. Some equations try to offset this by working in your body fat percentage.**Does not Reflect Metabolic Adaptations:**Our bodies adapt to changes in diet and exercise over time. Meaning your Resting energy expenditure can also change from the initial value.**No Replacement for Medical Advice:**While TDEE calculators are useful tools, they should not replace advice from medical professionals or dietitians, especially for those with medical conditions affecting metabolism.**Error Rate:**Error rates impact the amount of calories you actually may use. See below for more.

## Error Rate

Each formula comes with a margin of error as it only provides an approximation of calorie needs. It can be beneficial to have a range of calories in mind to compensate for these inaccuracies as a starting point. The majority of calculators employ the Mifflin-St Jeor equation, which is believed to have a 10% margin of error. For example, if the Mifflin-St Jeor equation indicates a daily usage of 2000 calories, the actual consumption could vary by up to 10% more or less than that. This equates to a 200 calorie variation, meaning the actual daily requirement could range from 1800 to 2200 calories.

**TDEE Takeaway**

TDEE calculators are a great and solid starting point in understanding the amount of energy you require each day. TDEE calculators provide a starting point to create diet and exercise routines uniquely tailored to our own body requirements.

All results from TDEE calculators should be considered an estimate and a good starting guideline. For a precise measurement of your energy requirements consider a lab test or using a resting energy expenditure tester, that way you know scientifically the base number of calories you need each day.

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