Your Metabolism 101 by Coach Colby Awalt
Our bodies are constantly undergoing metabolic processes throughout the day in order to burn energy (aka calories). Even as you are reading this article your body is burning energy to allow your eyes to scan the screen and hopefully sit with great posture. There are four general categories that make up our total daily energy expenditure (TDEE) including basal metabolic rate (BMR) or resting metabolic rate (RMR), thermic effect of food (TEF), exercise activity (EA), and non-exercise activity thermogenesis (NEAT). Now, let’s learn about each one and ways to maximize their efficiency.
Basal metabolic rate (BMR) or resting metabolic rate (RMR)
RMR provides the energy necessary for the functioning of your most integral organ systems including the liver, brain, and muscles. Outside of physical activity our bodies are burning calories in order to keep us alive and functioning properly. The body undergoes so many intricate and involuntary physiological processes every day. If you have ever taken an anatomy class before you will know the depth. This category comprises about 70% of your total daily energy expenditure. Interestingly enough, the brain is responsible for using up about one-fifth of RMR’s fuel (McCall, 2017). This is why you might feel some mental fogginess coming on whenever you have not eaten anything in a while.
Thermic effect of food (TEF)
Surely enough, your body burns energy in order to break down food within the digestive system. The energy burned from the thermic effect of food is around 10% of TDEE, but it is still important. Depending on which type of macronutrient is eaten (carbs, fats, proteins), the resulting energy burned from its digestion will differ. Protein has the highest thermic effect of food while fats have the lowest. This is why if you have eaten a lot of meat in one sitting it might have caused you to have the infamous “meat sweats.” The digestive system has to work a lot harder to break down meat or protein sources within your digestive tract. All the more reason to get your daily protein in folks. Not only will you be feeding your muscles but you will be burning additional calories through the digestive process as well.
Exercise Activity (EA)
Exercise activity is any purposeful exercise that requires the muscles to be used in a strenuous manner. Whenever I was first learning about these categories I was surprised by the staggering difference between exercise activity’s overall contribution towards TDEE compared to RMR. As revealed above, the bulk of your calories are burned from your RMR and not during a single workout. This category will differ depending on how physically active an individual is. A sedentary person’s metabolic contribution towards this component may only be 10-15% while a highly physically active person’s may be 30% (Berardi et al., 2018).
Workouts should be structured in a challenging manner in order to produce the “afterburn” effect. The afterburn effect basically enables your body to continue burning calories well beyond activity. This occurs due to your muscles being out of homeostasis and needing adequate replenishment of oxygen and nutrients. A fancy phrase called excess post-exercise oxygen consumption (EPOC) is what creates this whole process. Whenever exercise reaches a certain point of high intensity our muscles cannot continually be supplied with sufficient amounts of oxygen. This can create an “oxygen debt,” which must be paid back after exercise. This oxygen debt can be paid back within a few minutes, hours, or even days depending on how intense the physical activity was (Berardi et al., 2018).
This is why it is important to keep your workouts short and intense in order to create an increased calorie burn during the rest of your day (RMR). Additionally, building up your muscles by progressively overloading them during weightlifting will resultantly increase your RMR as well. Since muscle is a highly metabolic tissue, having more of it will never hurt if you are seeking to lose weight or maintain a lean or toned look. Thankfully, our workouts here at BCS Fitness do a really great job of providing the right stimulus for awesome EPOC and muscle building effects. So, keep getting your workouts in to see some awesome improvements in your muscle mass, health, fat loss, athleticism, balance, flexibility, etc.
Non-exercise activity thermogenesis (NEAT)
This category is by far my favorite (and not just because it has a cool acronym). The benefits it provides are widespread. You can think of NEAT as anything you do during your day that does not include planned exercise activities. This could include anything from gardening and taking out the trash to increased fidgeting due to that extra cup of coffee. While intentional exercise activity is what gets all the acclaim, I am here to highlight how NEAT can have a massive impact on your health and weight loss goals.
There is an important enzyme called lipoprotein lipase (LPL) that aids in converting fats into energy. Whenever someone is sedentary for a long period of time this enzyme will grow dormant. However, if NEAT is maintained consistently throughout your day then LPL will retain its functionality (McCall, 2017).
Many people think that exercising within the gym is the only form of physical activity they need during the day. Their thought process might go something like this: “Well, I already worked out this morning so it is okay if I take it easy and lounge the rest of the day.” I am here to tell you…don’t fall into this trap. What you accomplished in the gym may have helped you burn a few hundred calories (and that is great; be proud of yourself for putting in the work), but the rest of your day matters too. The more activity you can acquire throughout the day the better.
A critical and easy way to increase your NEAT is getting your daily steps in. Whether you have a daily step goal of 10,000 or not, acquiring more steps will not only provide additional health benefits but will aid in the calorie burning process. Now, you might be saying to yourself, “My job doesn’t allow me to have a high NEAT.” If you are someone who does not have a physically active job, then take frequent breaks. Get up from your desk and take a lap around the building or go fill up your water bottle at the dispenser across the room a couple of times. Sitting for prolonged periods of time has been shown through a growing number of studies to be detrimental to health (McCall, 2017). The less time you can spend sitting down will ultimately help your health and maybe your waistline too.
Also, look for random opportunities throughout your day where you can go out of your way to burn more calories. This might look like parking farther away from the grocery store entrance so you have to walk an additional few steps or taking the stairs instead of the elevator. If you are able to burn an extra 200 calories per day by increasing your NEAT and reducing your caloric deficit by 200-300 calories, then those lingering few pounds might slowly start diminishing.
I hope this blog was a helpful insight into how your body goes about utilizing energy through all of its metabolic processes. Get your workouts in, eat right, and move often. If you do these things consistently, then your metabolism will thank you.
Berardi, J. et al. (2018). The essentials of sport and exercise nutrition. Precision Nutrition.
McCall, P. (2017). 6 things to know about non-exercise activity thermogenesis. American Council on Exercise. Retrieved from https://www.acefitness.org/education-and-resources/lifestyle/blog/6852/6-things-to-know-about-non-exercise-activity-thermogenesis