Most people know of calories (also kcal) but do not truly understand how they work. Those that believe calories don’t matter also probably think the Earth is flat. Perhaps there is a disconnect. Let me explain.
It all comes back to thermodynamics which states that energy cannot be created or destroyed in an isolated system. Energy balance is the result of energy being transferred. You have likely heard the phrase “calories in, calories out” or “energy in, energy out.” This is what energy balance is all about: the difference between calories consumed and calories expended through activity. The result is body composition remains the same, being lost, or being gained.
Without getting too in-depth, I’m going to explain the factors that largely effect energy balance because ultimately this is the point people miss due to a lack of knowledge or understanding:
First off, each individual has their own Basal Metabolic Rate/Resting Metabolic Rate (BMR/RMR). These are the calories expended performing normal daily bodily functions such as breathing, circulating blood, and maintaining body temperature. BMR/RMR belong to the the “calories out” segment.
Also belonging to the “out” portion is the Thermic Effect of Activity (TEA) which is the energy put in to exercise or any other physical activity. There are many variables that effect this segment of “energy out” such as individual BMR/RMR, duration of activity, and intensity of activity.
Non-exercise Activity Thermogenesis (NEAT) or Spontaneous Physical Activity (SPA) refers to energy expended during involuntary actions throughout the day like fidgeting, obsessive compulsive behavior, or any other non-exercise tasks that aren’t typical bodily functions. Again, another component of the “energy out” segment of energy balance.
“Energy in” is a little more obvious. Your body has to breakdown and metabolize the food and beverages we consume which requires energy in varying amounts depending on the type of nutrients we are consuming. This is know as the Thermic Effect of Food (TEF) and is basically the energy expending metabolizing nutrients and non-nutrient sources such as protein, carbohydrates, fiber, fats, and alcohol.
One of the more important things to know about all of these factors and how they effect body composition is that they are never static figures. Due to natural changes in body stores (water, sweat, urine, poop, hormonal factors) from one day to the next as well as many other variables, it becomes much more complicated to track these figures. Again, there is a lot going on with inter-individual caloric expenditure.
I purposely didn’t elaborate on each of the factors effecting energy balance because it’s hard enough to keep the reader’s attention span for this long. However, if someone has specific questions about any of the above, I will answer the question(s) in detail and add to this post. Bring it!