How Does Your Body Burn Calories?

Your body can do many things, and one of those things is the ability to consume calories in order to later use them up throughout the day, this is thanks to your metabolism. Your body’s metabolism is very important to understand as it can provide you the advantage of being able to eat any diet while still progressing towards your fitness goals by understanding the amount of calories being burned within your body, and calories being consumed. In today’s topic, I’ll be covering the three different ways your body burns calories, as well as some more information regarding metabolism. Knowing this information can help you stay on track with your diet and understand how much your exercises is impacting your body.

It’s important to understand your own body and the chemical processes it undergoes, one particular process that is especially good to understand is your metabolism. Your metabolism is all of the biological processes that occur within your body within a 24 period in order to keep you alive. Your TDEE is the energy your body requires in order to process these biochemical processes. This energy is measured in calories, which your body burns calories in three different ways:

  1. Through simply being alive

What I mean by this is your Basal Metabolic Rate, or BMR. These calories are burned by your body simply maintaining itself, so like the amount of calories you would burn is you decided to literally just lay down and do absolutely nothing. These calories “amounts to 60 percent to 70 percent of the total calories you use daily”. The advantage of knowing your BMR is that you can “create a more effective strategy for weight loss, allowing you to better keep your calorie count on track and better understand the effect exercise will have on your waistline” (Thompson).

  1. Digestion

This is known as the thermic effect of food (TEF), or in order words your digestive metabolism. These calories burned come from the calories you eat, and as might’ve not known, the calories burned from food digestion varies based on the foods you eat. “Around 10-15% of the calories you eat is used to power digestion.” Foods that are highest in thermogenic effect – burn the most calories during digestion – are those high in protein; “20-30% of total calories in protein eaten go to digesting it, 10-15% for carbohydrates, and 0-3% for fats.” For example, if you eat 100 calories worth of protein, your body would burn 20-30 of those calories in order to digest it, leaving you with a net of 70-80 calories. (Petre & Kollias)

  1. Physical Activity

The leftover calories you get from your nutrition is used to fuel your everyday tasks. The calories burned from physical activity makes for the rest of your TDEE (Total Daily Energy Expenditure). There are two sub-categories that fall under the calories burned during physical activity, this includes: your workouts and NEAT (Non-exercise activity thermogenesis). Workouts are the intentional stress you add onto your body which allows it to burn more calories, and NEAT are for normal everyday tasks like walking, cleaning, reading, etc (Petre).

Your body uses the calories it gets from food in order to fuel your BMR, digestion, and physical activity. Thus, reinforcing the whole “calories in v. calories out” model that many people in the fitness industry follow.

Now, I know what you’re thinking, hey Sam this is great, but how to I even calculate these things in order to help me? Well thanks for asking, because luckily for you, researchers have created equations you can use in order to estimate these numbers.

How do I calculate the amount of calories I burn?

The fastest and easiest way to calculate your calories is by using an online calculator. However, you can also do the math yourself by using equations suggested by researchers

  • If you’re a man, your BMR is equal to: 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years). Example, if you’re 170 pounds, 5’11”, and 43, your BMR is 66 + (6.23 x 170) + (12.7 x 71) – (6.8 x 43) = 1,734.4 calories
  • If you’re a woman, your BMR is equal to: 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years). Example, if you’re 130 pounds, 5’3”, and 36, your BMR is 665 + (4.35 x 130) + (4.7 x 63) – (4.7 x 36) = 1,357.4 calories

Next figure out your total daily caloric requirement by multiplying your BMR by your level of activity:

  • If you rarely exercise, multiply your BMR by 1.2
  • If you exercise on 1 to 3 days per week, multiply your BMR by 1.375
  • If you exercise on 3 to 5 days per week, multiply your BMR by 1.55
  • If you exercise 6 to 7 days per week, multiply your BMR by 1.725
  • If you exercise every day and have a physical job or if you often exercise twice a day, multiply your BMR by 1.9

If the man in the example exercises 3 days a week, his daily caloric requirement is 1,734.4 x 1.55, or 2,688.3 calories.

If the woman in the example exercises 6 days a week, her daily caloric requirement is 1,357.4 x 1.725 or 2,342.5 calories.

This calculation gives you the number of calories you burn in one day at your current level of activity; this is the number of calories it takes to stay at the weight you are if you don’t change anything.” Now, based on your rough calculations, you can personally adjust your diet and training routine in order to meet your desired goal by adjusting your calories limit and exercise volume/intensity (Thompson).

What did you learn from this blog?

How will you implement your now acquired knowledge on metabolism in order to reach your goals?


Your body burns calories in three different ways: Simply being alive (BMR), digestion, and physical activity. Understanding the factors that affect your metabolism is essential as it can help you you personalize your diet and training routine in other to suit your goals or lifestyle.


Jr, ByDennis Thompson, et al. “Boost Weight Loss by Knowing Your BMR.”, 2010,

Kollias, Helen. “Research Review: A Calorie Isn’t a Calorie.” Precision Nutrition, 26 Sept. 2019,

Levine, James A. “Non-Exercise Activity Thermogenesis (NEAT).” Best Practice & Research. Clinical Endocrinology & Metabolism, U.S. National Library of Medicine, Dec. 2002,

Muir, Chris. “What Does TDEE Mean And How Do You Calculate It?” Caliber Fitness, 20 July 2018,

Petre, Alina. “’Calories in, Calories out’ – Does It Really Matter?” Healthline, Healthline Media, 20 June 2019,

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