“How many calories do I burn a day?” – you’ve probably thought of this before.
No matter what your fitness goal is – whether it’s to lose fat, gain muscle, or just maintain your weight – you definitely need to know how many calories you burn daily.
But why do you need to know this?
When you know how many calories you burn on a daily basis…
- You can determine how many calories you need to stop eating so you can lose weight. (What you call creating a calorie deficit.)
- You can determine how many more calories you need to eat so that you will have enough energy for those intense compound weightlifting and other exercises to gain muscle.
- You can balance the calories you eat and the calories you burn so that you keep your weight stable.
Let’s go into the various methods by which you can calculate the number of calories that you are burning.
How Many Calories Do I Burn a Day?
Two Scientific Methods for Measuring Energy Expenditure
The term “burning calories” is just the same as saying “burning energy.” This energy that you burn is what you call ENERGY EXPENDITURE.
There are two methods by which scientists measure energy expenditure.
The first method is called Indirect Calorimetry, which is considered the gold standard for the measurement of energy expenditure. In this method, the amounts of oxygen and carbon dioxide during respiration are measured and the values obtained are used to calculate energy expenditure.
This method is touted to be the most accurate scientific procedure based on the fact that there is a direct relationship between the body’s use of these gases and the amount of energy that is being burned. Oxygen and carbon dioxide are needed in the creation of energy. Hence, they are essential to life. It should be mentioned though that your body only uses small amounts of these gases, with the majority being released through exhalation.
If this seems confusing to you, allow me to simplify it. If you need a lot of energy, your body, particularly your respiratory system, will inhale more of these gases. BUT, because of the large demand for energy, you will be exhaling less. Now, if you are at rest, you will be inhaling these gases normally, but because there is a minimal demand for energy, you will be exhaling out more. This inhalation and exhalation of oxygen and carbon dioxide is what Indirect Calorimetry is measuring.
The second method utilizes Doubly Labeled Water (DLW). In this method, the individual is made to drink a kind of water that contains compounds that are retained inside the body for a short period of time. The rate of elimination of these compounds through sweat, urine, and saliva is measured and the value is used for the computation of the metabolic rate.
While both of these methods are very accurate, their main drawbacks are that they need to be performed in a laboratory under the supervision of research specialists and they are also very expensive. Not practical at all for your daily fitness activities.
Using Fitness and Activity Trackers
A lot of fitness enthusiasts love to use fitness and activity trackers to monitor the calories they are burning. There’s also the fact that these trackers are also great fashion accessories, making the wearer look sporty and hip.
BUT…are these devices as accurate as their manufacturers claim in their ads?
All fitness trackers are equipped with an accelerometer, an instrument that shows the wearer their movement’s velocity. The accelerometer detects movement which then produces data. This data is calculated through an algorithm programmed into the device to provide an estimate on the number of calories that particular movement caused you to burn.
However, the problem with these devices is that they are calibrated for one specific activity. Use it on other forms of activity, and it will give you an imprecise reading. For example, pedometers will only give you an accurate of your calories burned if you walk at a particular pace. Accuracy is lost when you start walking slower or faster.
These devices are even more useless for intensive exercises like weightlifting wherein not too much physical motion is involved. However, if you compare weightlifting to walking, more calories are burned off by the former instead of the latter. This was demonstrated in a 2015 review of FitBit and Jawbone, two popular fitness trackers. Both of these trackers were able to measure energy expenditure with some accuracy, but they give low and inaccurate measurements for calories burned. These same findings were also noted with pedometers.
These fitness trackers are only recommended when measuring the number of calories burned for activities like walking. For other activities like weightlifting, expect the readings to be off by 50 percent or more. Fitness tracking apps in smartphones are not much good either, with research showing their readings to be off by 30 to 50 percent or more.
What about those fitness trackers that you wear around your chest? These devices estimate the number of calories burned by counting the heart rate. They are found to be more accurate than wrist trackers and smartphone apps because the computation of the calories burned takes into account the person’s age, body weight, and resting heart rate. But, many fitness enthusiasts don’t like to wear these devices strapped to their chest. There is a variation device that measures the pulse on the wrist, but they are not as accurate as the chest heart rate trackers.
Don’t expect too much from these fitness and activity trackers. They will only give you a rough estimate of the calories that you burn.
Using Workout Machines
A lot of people love their cardio workout machines, whether they have one at home or they use the machines in the gym. They love how these machines flash readouts of the number of calories burned, so that they would know if they are meeting their fitness goals.
Are these machines any better than those fitness trackers?
You’ll be shocked, but the answer is NO! While fitness trackers often underestimate the number of calories you burn, workout machines OVERESTIMATE your calorie burn readings.
Why is this so? First of all, manufacturers of these workout machines program different algorithms, so that machines of competing brands will give you varying results.
Second, these machines do not take into account other factors that affect how much calories you burn, namely age, weight, gender, and fitness level. Look at it this way. Let’s say that you exert the same effort and work out at the same duration (like 30 minutes or any hour or so). If you’re lean and fit, expect to burn less energy. However, if you’re on the chubby side expect to burn more energy.
Third, these machines take quite a beating after years of use. Take treadmills for example. As time passes, the resistance of the belts decreases, so that there is less traction and you burn less energy when you use them.
Fourth, fitness experts forget to factor in user error. You can expect the machine to cough up a smaller “calories burned” value if you have the tendency to lean on the handrails of the treadmill, elliptical machine, and stair stepper to maintain your balance. The reason for this is that reduce the weight your muscles need to move. Another common user error is upper body passivity while using an elliptical machine. What do I mean by this? You are keeping your upper body passive if you are just holding on to the handles and let your lower body do all the work. An active upper body is when you pump your arms as you push the handles to and fro. Even if you are passive, the machine makes the automatic assumption that you are pumping your arms, so that it gives you an inaccurate result.
Just how big is the overestimation of the calories burned by these workout machines? Here are the findings in a study done by the researchers of the Human Performance Center of the University of California-San Francisco…
- Stationary bicycles = overestimation by 7 percent
- Stair climbers = overestimation by 12 percent
- Treadmills = overestimation by 13 percent
- Elliptical machine = overestimation by 42 percent
Calculating the Calories You Burn During Exercise –
How Many Calories Do I Burn a Day?
We have now come to this part of the article when you need to whip out those calculators. Don’t worry. I promise it will be painless.
The key to calculating the calories you burn during exercise or other physical activity is METABOLIC EQUIVALENT OF TASK (MET).
As you know, a calorie is defined as the amount of energy needed to heat one kilogram of water by one degree Celsius. MET is similar to a calorie, except that it measures the amount of energy that an average person will burn while at rest for one minute.
Each activity that you do in your daily life has a corresponding MET score. Thankfully, you can find these scores in The Compendium of Physical Activities Tracking Guide. This compendium contains the MET scores of every physical activity, ranging from just sitting still (score of 2) to running at 10 mph (score of 18). If you’re wondering about weightlifting, the MET score ranges from 3 to 6.
Now, let’s go through the steps of calculating your calories burned during exercise.
1) Know the MET equation.
Here’s the equation for determining the number of calories burned using MET…
MET x Your Weight in Kilograms x Hours of Activity = Number of Calories Burned
2) Check the MET score of the activity you’ll be measuring.
Let’s say you want to check the MET score of weightlifting. For this example, we’ll use the maximum score of 6.
If you will be checking the MET score of other activities, like running, take note of the intensity of the activity. For example, running at 5 mph has an MET score of 7, but if you amp it up to 10.9 mph, your MET score rises to 18.
3) Fill in your values in the MET equation above.
Your weight is 90 kilograms, or approximately, 198 pounds. You spend one hour on weightlifting. Place these values in our MET equation and you have…
6 METs x 90 kgs x 1 = 540 calories burned
Based on the results, you burn 540 calories every hour that you do weightlifting. Please note that this is an APPROXIMATE value since you might be burning less or more energy during your workouts. Let’s say that, in that one hour, you spend more of that time resting on the bench.
If your workout consists of several exercises, calculate the calories for each exercise and then add everything up to get your TOTAL CALORIC EXPENDITURE. Let’s get some more examples from the Compendium.
- Boxing on a punching bag = 540 calories per hour
- Rope jumping = 720 calories per hour
- Leisurely swimming = 540 calories per hour
To these figures, add your earlier result on weightlifting and your total caloric expenditure for exercise is 2,340 calories.
Determining the Number of Calories You Burn Daily
Okay, we talked about the number of calories you burn during exercise. Now, just how many calories do you burn on a daily basis?
TOTAL DAILY ENERGY EXPENDITURE (TDEE) is the total number of calories you burn each day.
For a person who’s age 21, with a height of 6 feet 2 inches and weight of 195 lbs, and who lifts weights for 4 hours and high-intensity interval cardio for 1 1/2 hours weekly, the TDEE is estimated at 3,000 calories burned per day.
There are three key components to TDEE…
- Basal metabolic rate = the amount of energy that the body burns at rest
- Energy burned through physical activity
- Energy burned from the digestion and absorption of food (also known as the “Thermic Effect of Food” or TEF) = comprises 10 percent of the TDEE, with the amounts varying depending upon your diet’s macronutrient composition.
To calculate the number of calories you really burn every day, just do the following…
- calculate BMR using an online calculator, such as the one found here
- calculate the calories burned in all your daily physical activities using the above MET equation
- Add the results and increase the sum by 5 to 10 percent (representing TEF)
Another great way to calculate your TDEE is through the Katch McArdle Formula, which I have personally found to be more accurate. However, I don’t recommend using this formula if you’re very physically active (getting 10 hours of vigorous exercise weekly) or you experience fluctuations in caloric expenditure on a day to day basis (such as when you do several hours of exercise on one day and then no physical activities the next day).
You should also keep track of the calories you eat daily. If you wish to lose weight, you should eat less than your TDEE. If you want to build muscle and gain weight, you should eat more than your TDEE.
While it is not really that necessary to get the exact figure of your TDEE, even a close approximate figure will enable you to do wonders on your body composition.
Use your estimates to develop meal plans that will help you to achieve your fitness goals.
You can find an awesome three-day meal plan you could use just at the bottom of this article.
Again, if you want to lose weight, you should eat fewer calories than what you are burning. If you want to gain weight, you should eat more calories than what you burn.
If you’re still asking “How many calories do I burn a day?“… It’s pretty simple, isn’t it?