Your metabolism is based upon several different energy systems or components. To optimize your body composition, with calories or macros, it is important to understand how your body utilizes energy from food. These energy systems include, basal metabolic rate (BMR), exercise activity (EA), the thermic effect of food (TEF), and non-exercise activity thermogenesis (NEAT), to calculate and understand your total daily energy expenditure (TDEE).
What Is Basal Metabolic Rate (BMR)
Basal metabolic rate is the number of calories your body needs to accomplish its most basic (basal) lifesustaining functions.
Basal metabolic rate (BMR) is the smallest amount of calories/energy that our bodies need to sustain and support vital functions. This does not account for any activity outside of keeping us alive, meaning beating our heart, breathing, blinking our eyes, and so on. Nearly 70% of the energy we expend every day goes towards nonmovement related physiological activity, like breathing, and this is what BMR accounts for.
What Is Resting Metabolic Rate (RMR)
You may have also heard of RMR. Similar to BMR, resting metabolic rate (RMR) is found by measuring oxygen consumption at rest. RMR will typically be higher than BMR but only by no more than a 10% difference. Things that contribute to this change are small amounts of movement, various environments, and digestion.
Thermic Effect Of Food (TEF)
Exercise activity (EA) is simply the amount of energy the body uses and requires to support purposeful exercise activity, like running or lifting weights. This amount varies from person to person. For example, for a sedentary person, EA can account for 10-30% of daily energy demand from food, while other, more active individuals, can require more than 30% of their daily energy demand from purposeful activity. The higher intensity the exercise has, the more calories your body needs both during and after exercise. As post-exercise oxygen consumption increases (EPOC), so does the demand for the body to replace oxygen and nutrients lost during activity.
What Is Exercise Activity (EA)
Exercise activity (EA) is simply the amount of energy the body uses and requires to support purposeful exercise activity, like running or lifting weights. This amount varies from person to person. For example, for a sedentary person, EA can account for 10-30% of daily energy demand from food, while other, more active individuals, can require more than 30% of their daily energy demand from purposeful activity. The higher intensity the exercise has, the more calories your body needs both during and after exercise. As post-exercise oxygen consumption increases (EPOC), so does the demand for the body to replace oxygen and nutrients lost during activity.
What Is Non-Exercise Activity Thermogenesis (NEAT)
Non-exercise activity thermogenesis (NEAT) includes all of your daily movement that is not exercise activity (EA). This includes things like getting up from your desk to go to the restroom, driving a car, fidgeting at your desk, playing with kids, going for a walk, carrying groceries, etc. If you’re looking to optimize the amount of calories you use throughout the day, increasing your NEAT, especially if you’re sedentary throughout the day, can contribute positively towards your health and fitness goals.
Total Daily Energy Expenditure (TDEE)
Your metabolism is calculated using what’s called Total Daily Energy Expenditure (TDEE). TDEE is comprised of three key components; resting metabolic rate (RMR), the thermic effect of food (TEF), and the thermic effect of physical activity (TEPA). TEF is the energy expended when chewing, swallowing, digesting, and absorbing food. TEPA is the energy of activity, during and not during exercise.
RMR = BMR + metabolic maintenance activity and physical activity = EA + NEAT
TDEE = RMR + physical activity + TEF
If you want to lose weight eat less than your TDEE
If you want to maintain weight eat at your TDEE
If you want to gain weight eat more than your TDEE
You can measure your TDEE by using our calculator here Total Daily Energy Expenditure (TDEE) Calculator
Why You Need To Calculate Your BMR
By determining your BMR and TDEE you can predict, within reason, how many calories you need to eat in a day to lose, maintain, or gain weight. Knowing how many calories you burn (BMR) at rest provides a baseline to eat above to support vital functioning, while your TDEE provides an upper limit on what you need daily to sustain your lifestyle and exercise. You do not want to eat less than your BMR ever.
What Happens If You’re Not Getting Results
Our bodies are amazing, complicated systems. Sometimes it isn’t as straightforward as calories in vs calories out and we need to account for other things, like TEF (what our food is made up of i.e. eating more protein not just more calories), EA (introducing an exercise routine), NEAT (going for more walks through the day instead of sitting for 8 hours), and understanding your TDEE. If you’re not getting results on your own, it is time to consult a nutrition coach, so you can achieve efficient results from your efforts.
Further Nutrition And Training Resources
If you have additional questions or need help with your nutrition and training, you can schedule a free personal nutrition consultation with one of our certified nutrition coaches from The Swole Kitchen (TSK)
Or if you’d like to learn more on your own, visit our fitness and nutrition blog with any questions you may have. We have a large library of content and resources.