Calculating how many calories are burned in a day
For a person to lose weight, they must burn more calories than they take in, creating a calorie deficit. But, to do this, they need to know how many calories they burn each day.
In this article, we take a look at how someone can work out how many calories they burn in a day.
What is a calorie?
The three main food groups — proteins, carbohydrates, and fats — have different calorie contents. Most food products will display the nutritional content, including calories.
Most people think of calories as only having to do with food and weight loss. However, a calorie is a unit of heat energy. A calorie is the amount of energy that is needed to raise 1 gram (g) of water by 1°C.
This measurement can be applied to lots of different energy releasing mechanisms outside of the human body. For the human body, calories are a measure of how much energy the body needs to function.
Food contains calories. Different food has different calorie counts, meaning that each food has a different amount of potential energy.
There are three basic types of foods that make up all the food that humans eat: carbohydrates, proteins, and fats. These three different types of food have varying amounts of potential energy per g.
The calorie breakdowns per g for each food type are as follows:
- Carbohydrates: 4 calories per g
- Proteins: 4 calories per g
- Fats: 9 calories per g
Calculating daily calorie burn
Calculating calories consumed and burned up may help with weight management. Various apps and websites are available to aid this process.
Being able to work out how many calories are burned each day is essential to any person looking to maintain, lose, or gain weight.
Knowing what factors contribute to calorie burning can help a person alter their diet or exercise program to accommodate the goal.
An accepted method to calculate how many calories a person burns each day is the Harris-Benedict Formula.
Originally developed in the early 20th century, it was revamped in 1984 and again in 1990 to help 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 by simply existing. BMR varies based on age, sex, size, and genetics. To calculate BMR, a person uses inches for height, pounds for weight, and years for age in the following formulas:
- For men: 66 + (6.2 x weight) + (12.7 x height) - (6.76 x age)
- For women: 655.1 + (4.35 x weight) + (4.7 x height) - (4.7 x age)
The results of the BMR calculation are then used to multiply against the average daily activity of the person. Points are awarded based on how active a person is.
Points for activity levels are as follows:
- 1.2 points for a person who does little to no exercise
- 1.37 points for a slightly active person who does light exercise 1–3 days a week
- 1.55 points for a moderately active person who performs moderate exercise 3–5 days a week
- 1.725 points for a very active person who exercises hard 6–7 days a week
- 1.9 points for an extra active person who either has a physically demanding job or has a particularly challenging exercise routine
When the BMR is calculated and the activities points are determined, the two scores are multiplied. The total is the number of calories burned on an average day.
For example, to calculate how many calories a 37-year-old, 6-foot-tall, and 170-pound man who is moderately active burns, the formula would look like:
(66 + (6.2 x 170) + (12.7 x 72) - (6.76 x 37)) x 1.55 = 2,663 calories/day
This figure shows that a man of this age, height, weight, and activity level can consume 2,663 calories and maintain his current weight. He could increase or decrease weight by consuming more or less than this amount over the course of several days.
For those who do not wish to make the calculations themselves, there are a range of calorie calculators available online. Most use a similar formula to work out calories burned.
A doctor or nutritionist should also be able to help people work out how many calories they burn each day.
Factors affecting calorie burn
Many factors affect how many calories a person burns each day. Some of the factors that influence daily calorie burn are not in a person's control while others can be changed.
These factors include:
- Age: the older a person is, the fewer calories burned per day.
- Sex: men burn more calories than women.
- Amount of daily activity: those who move more, burn more calories.
- Body composition: those with more muscle burn more calories than those who have less muscle.
- Body size: larger people burn more calories than smaller 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.
- Breast-feeding: women who are breast-feeding also burn extra calories.
Calories burned by exercise or activities
All activities use up calories, even housework such as vacuuming. More intense physical activity such as aerobics will burn more calories.
Calorie counts for exercise and activity will vary from person to person. Age, sex, body type, and size influence how many calories an individual will burn doing a physical activity.
In general, more intense or strenuous activity will burn more calories than lighter effort exercise.
The following calorie counts are based on a 155-pound person doing the following exercise or activity for 30 minutes:
- aerobics: 211
- stationary bike (light effort): 176
- stationary bike (moderate effort): 247
- dusting: 70
- gardening: 176
- grocery shopping: 106
- hiking: 211
- house cleaning: 106
- jogging: 247
- running 12-minute miles: 282
- running 10-minute miles: 352
- running 7.5-minute miles: 428
- laundry, including folding clothes: 70
- mowing the lawn (no riding mowers): 141
- playing with kids at the playground: 141
- cooking: 70
- raking: 141
- shoveling snow: 211
- tennis (singles): 282
- vacuuming: 70
- brisk walking: 141
- walking while pushing a stroller: 70
- weightlifting: 106
- yoga: 141
Anyone that wants to figure out how many calories they burn can input their statistics into a calorie calculator and find personalized results.
People looking to lose weight should try to create a calorie deficit by following these tips:
- moving more
- eating a lower calorie diet full of healthful fruits, vegetables, and lean proteins
- getting enough sleep
- drinking more water
Losing weight can be very tough to do. Understanding how many calories an individual's body burns per day and what to do to increase daily calorie burn is the key to success.