The number of calories burned each day is directly related to weight loss, weight gain, or weight maintenance. For a person to lose weight, they must burn more calories than they take in, creating a calorie deficit. But, for that, she needs to know how many calories she burns each day.
In this article, we will see how we can calculate the number of calories she burns in a day.

What is a calorie?

The three main food groups: proteins, carbohydrates and fats have different calorie contents. Most food products display nutritional content, including calories. Most people think that calories have nothing to do with food and weight loss. A calorie is a unit of thermal energy. A calorie is the amount of energy needed to raise one gram of water by 1°C. This measurement can be applied to many different energy release mechanisms outside of the human body. For the human body, calories are a measure of the amount of energy the body needs to function.

Calories from proteins, carbohydrates and fats

Foods contain calories. Each food has a different number of calories, which means that each food has a different amount of potential energy. There are three basic types of food that make up all food consumed by humans: carbohydrates, proteins and fats. These three different types of food have varying amounts of potential energy per gram.

The breakdown of calories per g for each type of food is as follows:

Carbohydrates: 4 calories per g
Protein: 4 calories per g
Fats: 9 calories per g

Calculate daily calorie expenditure

Calculating calories consumed and burned can help with weight management. Various apps and websites are available to facilitate this process. Being able to calculate the number of calories burned each day is essential for anyone looking to maintain, lose or gain weight.

Knowing the factors that contribute to calorie burning can help a person modify their diet or exercise program to achieve their goal.
A recognized method for calculating the number of calories a person burns each day is the Harris-Benedict formula. Originally developed in the early 20th century, it was revised in 1984 and again in 1990 to improve its accuracy.

The Harris-Benedict formula is a relatively simple process in which a person multiplies their basal metabolic rate (BMR) by their average daily activity level.

BMR is the number of calories a person burns simply by existing. BMR varies with age, gender, height, and genetics. To calculate BMR, a person uses Meters for height, Kilos for weight, and Years for age in the following formulas:

Male = 13.7516 x Weight(kg) + 500.33 x Height(m) – 6.7550 x Age(year) + 66.473.
Female = 9.5634 x Weight(kg) + 184.96 x Height(m) – 4.6756 x Age(year) + 655.0955.

The results of the BMR calculation are then multiplied by the person’s average daily activity. Points are awarded based on how active a person is.

The points for activity levels are as follows:

1.2 points for a person with little or no activity
1.37 points for a mildly active person who does light exercise 1-3 days a week
1.55 points for a moderately active person who does moderate exercise 3-5 days a week
1,725 ​​points for a very active person who does intense exercise 6-7 days a week
1.9 points for a very active person who has a physically demanding job or who practices a particularly difficult physical exercise.

When the BMR is calculated and the activity points are determined, the two scores are multiplied. The total is the number of calories burned in an average day.

For those who don’t wish to do the calculations themselves, there are a variety of calorie calculators available online. Most use a similar formula to calculate calories burned.

Factors Affecting Calorie Expenditure

Many factors influence the number of calories burned each day. Some of the factors that influence daily calorie expenditure are beyond a person’s control, while others can be changed.

These factors are:

Age: the older a person is, the less calories they burn per day.
Gender: Men burn more calories than women.
The amount of daily activity: those who move more burn more calories.
Body composition: People with more muscle burn more calories than those with less.
Body size: Tall people burn more calories than short people, even at rest.
Thermogenesis: This is the amount of energy the body uses to break down food.
Pregnancy: Pregnant women burn more calories than non-pregnant women.
Breastfeeding: Breastfeeding women also burn extra calories.


Harris, JA, & Benedict, FG (1918, December). A biometric study of human basal metabolism. Proceedings of the National Academy of Sciences of the United States of America, 4(12), 370–373

Mifflin, MD, St. Jeor, ST, Hill, LA, Scott, BJ, Daugherty, SA, & Koh, YO (1990, February). A new predictive equation for resting energy expenditure in healthy individuals [Abstract]. American Journal of Clinical Nutrition, 51(2), 241-247

Roza, AM, & Shizgal, HM (1984, July). The Harris Benedict equation reevaluated: Resting energy requirements and the body cell mass [Abstract]. American Journal of Clinical Nutrition, 40(1), 168–182

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