Metabolism is one of those terms that people will use but not fully understand what it means. The term is mostly associated with how well you can maintain weight or lose weight. Fast and slow metabolisms are commonly phrased when talking about losing weight. The word metabolism means much more than just losing or gaining weight. Your body’s metabolism is actually the total energy expenditure (TEE) of the body. What this means is that throughout the day, your body is burning energy to function. For example, all of your organs require energy to function properly. The body uses energy to perform, everything from breathing, digesting, and moving uses energy.   Each person can experience different metabolic rates due to genetics, lifestyle, height, weight, and age. 

The energy needed for the body to function, perform, and move is measured as calories. Calories can be defined as the energy needed to raise the temperature of 1 gram of water through 1 °C. To put simply, it is a unit of heat. The body uses this energy known as calories to function and that is the metabolism. Your metabolism can be broken into 3 categories: Resting Metabolic Rate (RMR), Thermic Effect of Food (TEF), and energy cost of physical activity. The total of these 3 categories is known as Total Energy Expenditure (TEE) or Total Daily Energy Expenditure (TDEE). 


Let’s break it down and talk more about RMR. The body’s RMR will be the bulk of the calories burned throughout the day. RMR will consist of about 60%-80% of total calories burned during the day. This means at complete rest your body will burn 60%-80% of total calories just to function. The body’s RMR will roughly be the same from day to day, and you can work towards increasing your RMR by increasing muscle mass. By adding just 1lb of muscle to your body, you can increase your RMR. The amount it goes up is not very clear but the actual number doesn’t really matter, the important part is that it will increase your RMR. The more muscle you gain the more calories you burn at rest. You are investing in your body to work with you.  The only form of exercise that increases muscle mass is strength training. This is why strength training should be the priority, it is a pro-tissue activity. 


The next component of TEE will be the energy cost of physical activity. Movement of the body, whether its exercise or normal activity will consist about 20%-30% of total calories burned for the day. Physical Activity can be broken down into two subcategories, Non-Exercise Activity Thermogenesis (NEAT), and planned exercise activity. NEAT is all of the physical movement that you do during the day that is not considered exercise. This includes sitting and standing, walking around the house, cleaning the house, etc. Exercise is a planned activity that can be running, biking, hiking, resistance training, HIIT, etc. Comparing both activities, you will find that NEAT is significantly greater than exercise when it comes to total calories burned for the day. A rough breakdown would be about 15%-20% would be NEAT and 5%-10% would be from exercise. What does this mean for fat loss? It means that you cannot rely on exercise alone to burn enough calories to lose fat. Increasing your NEAT will burn more calories overall for the day than exercise alone. With exercise, you would want to do strength training with an emphasis to build more muscle mass. You need to look at strength training as a long term investment. The calories burned from exercise are short term, but the results from a consistent plan over time will result in more muscle. Building more muscle will help you build your RMR which will burn more calories with no effort. 


Let’s talk about the last component of TEE, which is going to be the thermic effect of food. This is the smallest energy expenditure with only about 10% of TEE is from the digestion of food. The digestion of food requires energy, very similar to the saying of “have to spend money to make money”, same thought process. To take the energy out of the food, the body has to spend a little energy to get it. The cool thing is that each macronutrient requires a different amount of energy to digest and absorb. The macronutrient fat takes about 3% of the consumed calories for it to be digested. For example, if you eat 100 calories of fat, the body will burn roughly 3 calories to process that fat. Carbohydrates can be between 5-10% of TEF and protein is the highest at 20%-30%. As you can see, protein takes significantly more calories to digest than the other macronutrients. Using the same example as fat, the body would use about 20-30 calories to process 100 calories of protein. For a fat loss strategy, it would be highly beneficial to increase your protein intake for the thermic effect alone. Another reason protein should be increased is to help the muscles recover and grow from resistance training. As I mentioned before, strength training helps build muscles, and more muscle builds up the RMR. This will result in burning more calories with less effort. Your muscles can not grow and adapt if they do not have the proper nutrients from protein. 

Final Thoughts

So, what is metabolism? It is your body using energy for a variety of functions to survive. We saw that it takes energy for your body to function internally with all the organs doing its job. The body requires energy to move in its environment, whether that is in the form of exercise or just day to day activities. Even the breakdown and absorption of food requires energy for it to take place. A person’s metabolism can be manipulated to where the body requires more energy to function. This is done by resistance training to build muscle. The body burns calories while exercising, uses energy to repair and grow muscle, and it takes energy to maintain that muscle. This alone will drive your metabolism to be higher. Let us not forget about increasing our NEAT and protein consumption. NEAT has a bigger influence on our TEE than exercise alone, and protein requires 30% of its own energy to be consumed just to process it. Your lifestyle has a major influence on how your metabolism functions. If you want a faster metabolism then look at your lifestyle. Are you doing strength training? Are you consuming enough protein? Are you moving throughout the day? Ask yourself these questions and see where you can do better to improve your metabolism.

3 thoughts on “WHAT IS METABOLISM?

Leave a Reply