#12 Nutrition Principles Pt.1

Okay, so I wanted to start sharing some of the fundamental principles of nutrition the next few weeks.  Keep in mind that these principles are concepts that I hope everyone will get familiar with, if not already, and will always consider when trying to lose or gain weight, build muscle, and beyond.

The first principle, which I hope everyone’s heard of, is the concept of energy balance AKA calories in vs. calories out.  Yes, a simple version that we’ve all heard of is if you eat more calories compared to the calories burned you’ll lose weight and vice versa.  But is this true? I want to spend some time breaking down the science behind this concept of energy balance and see if that statement is correct.

First of all, what is a calorie? A calorie is defined as a unit of heat energy, more specifically the energy needed to raise the temperature of 1 gram of water through 1 °C.  Why I wanted to start here is because I want you to realize that a calorie isn’t a unit of weight, meaning 100 calories doesn’t equal to an amount of weight of fat or muscle.  Next, when talking about calories, the unit of heat energy like mentioned above, we are dealing with the laws of thermodynamics.  According to these laws (in simpler terms since I’m not a physicist and need to dumb it down for myself) energy is never really created nor destroyed but rather transferred or converted from one form to another. What that means is if we eat an apple the energy (calories) from it gets transferred into our bodies (calories in), and when we exercise energy gets transferred out of our bodies (calories out).

So if calories aren’t related to my weight why do I need to know this information? I just want to lose weight!

Actually, the relationship between the amount of calories we eat and the amount of energy we use determines our body weight.  If the body detects an energy deficit (less calories in than out) then the body figures out a way to make up that energy “shortage” by finding another source, such as our fat reserves! The energy deficit state is also known as hypocaloric. On the other hand, when there is an energy surplus (more calories in than out) the body finds a way to store the “excess” calories, hypercaloric. If the body detects an equal amount of calories in and out, isocaloric, the body doesn’t need to change anything and can just “maintain” itself.  It is important to know that fat isn’t the only form the energy gets converted to or from in the body but I’ll go over that in a different post.

As I mentioned above there are three states of energy balance:

  1. energy deficit (hypocaloric): calories in < calories out
  2. energy surplus (hypercaloric): calories in > calories in
  3. energy maintenance (isocaloric): calories in = calories out

Awesome.  So now it’s time to look at each side of the energy balance equation.

Energy-in has two components: calorie intake from the foods and drinks consumed and the amount of energy undigested and unabsorbed.

Energy In = Calorie intake – Energy undigested & unabsorbed

With all the examples discussed above, it should be pretty clear that the foods and drinks we consume are directly related to the energy-in.  However, the not-so-clear part is how much of that calories is actually being digested and absorbed and undigested & unabsorbed for that matter.  I don’t want to go too in-depth on what affects the energy undigested & unabsorbed because, well, way smarter people teach and do research on this issue like the gut microbiome.  However, I still wanted to mention it because now we can understand that even if we perfectly measure the exact calories consumed of our foods and drinks the energy-in value can vary due to the digestion and the absorption process.  It’s just another way of saying that the calorie counting is not going to be perfect and everything will be an estimation.

Now, onto the energy out.  This also is quite complex but I’ll try my best to simplify it.  I know this is a lot of information but hang in there.

The first component of energy expenditure is for staying alive.  What I’m referring to is the Basal Metabolic Rate (BMR) and it’s the energy we spend, mostly subconsciously, to stay alive, like the heart beating, keeping posture, and countless more.  Some studies have shown the BMR to actually contribute up to 70% of our total daily energy expenditure (TDEE)!!! Can you believe that? We don’t have control up to 70% of the energy use! That’s probably why it’s so hard to lose or gain weight.  However, we can control the following variables, some more than others, so let’s go over them.

Next component of the energy expenditure is called the Thermic Effect of Food (TEF).  Simply put, it is the energy required for eating.  When we eat we have to go through various processes such as ingesting, absorbing, metabolizing, and storing nutrients from food.  The TEF was found to have about 10% contribution to the TDEE.  I know what you’re thinking, “I can’t control these processes,” and yes, I agree.  However, the component which we do have control over is the type of food we eat.  Since this post is only about the energy balance I’ll go over the specifics of how the type of food impacts the TEF.

The next component is what we are the most familiar when it comes to “burning calories”: exercise!!! It is also called Thermic Effect of Activity (TEA) or Exercise Activity Thermogenesis (EAT) (fancy, huh?).  The TEA is the amount of energy we use via activities which include walking, carrying groceries, strength training, cardio, and more.  The TEA has the greatest variability out of all the components and it makes sense.  An elite athlete who trains multiple times a day can burn 1500 calories no problem while a sedentary person who works at a desk-job all day may only burn a hundred calories in their rare workout.

Beside from the three components discussed above (BMR, TEF & TEA) there is another way to expend calories, which is called Non-Exercise Activity Thermogenesis (NEAT).  What I’m referring to is the subconscious (mostly) activities like moving around, fidgeting, changing postures, and etc.  Since this is mostly subconscious, it is highly variable depending on the individual, ranging anywhere between 200-900 calories of expenditure per day.

Okay.  Let me summarize.

Energy out = BMR + TEF + TEA + NEAT

If we put all the components together it looks like:

Calorie intake – Energy undigested & unabsorbed = BMR + TEF + TEA + NEAT

It isn’t so simple as calories in vs calories out, right?

This is a lot of information but this is only the basics of nutrition.  What I’m trying to say is that you don’t have to remember all the details.  However, calories do matter and we need to respect the principle of energy balance when talking about nutrition and diet.  So next time you hear “you should go on a keto diet” or “have you tried the Whole 30 diet” keep in mind that the energy balance principle should and must be considered.

Diet - apple and measuring tape

My intention for this post is only to be an informative blog post, not any type of official publication of any sort, thus no proper citation.  However, here some of the resources I’ve learned from so check it/them out:



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