We're probably all familiar with the idea of calorie balance. Personally, it's something I've been hearing about from all types of sources my entire life:
- As a kid I saw it on television with shows like The Biggest Loser, where losing weight was all about restricting energy intake and working out as hard as possible. Somewhere along the way in a health class, I was formally taught that weight, and in turn, health, was managed by controling how much we eat and how much we exercise
- As I grew up, I learned how I could implement this framework in my life:
- Using the calories on food labels or menu items to judge a food selection
- On exercise machines to judge how good my workout was
- As an adult, it's everywhere:
- All over Instagram - how to measure a food's caloric value; calorie-torching exercises
- In
- Even in a graduate-level course I took on obesity! (I'll share that story in the audio below if you care to listen)
Insert audio here.
The point is, calorie balance has thoroughly engrained itself into out society. Why is this?
AUDIO OUTLINE:
Let's jump in by addressing this first question: Where does the idea of calorie balance come from?
Calorie balance arises out of the 1st law of thermodynamics, the conservation of energy. (Note: this is why it gets its credibility - because who can argue with the laws of nature?)
The 1st Law of Thermodynamics tells us that energy is conserved - since it cannot be created nor destroyed, then the difference between the energy that enters into a system and the energy that exits the system must be accounted for by energy stored within the system.
We can apply this to any generic system:
More useful for our purposes is to apply it to the human body as a defined system:
Finally, let's look at some examples of what that internal energy really is. To name the more important sources of internal energy, we have:
- Fat stored within the body - this is most common in subcutaneous adipose tissue, although it may also be stored "ectopically" in muscle tissue, the liver, and in or around organs
- Glycogen stored in the liver or muscle tissue - glycogen is simply a chain of glucose molecules; this is how carbohydrates are readily stored
- Any physical structures, whether that's protein, carbohydrate, or fat based - yes, all of these macronutrients can play a role as an energy source, but they also play roles structurally and functionally throughout the body
- Circulating energy - fats, lipids, and protein circulating through the bloodstream
Of course, energy is taken in through our ingestion of food; energy is expended in many different ways (something we'll dive into deeply in the next lesson).
Now, let's take a deeper look at the balance piece:
Here's our equation, taken straight from the conservation of energy:
Energy In - Energy Out = Change in Internal Energy
Which, we can readily translate to the following when applied to the human body:
Calories In - Calories Out = Change in Body's Internal Energy
What this equation is, simply, is a statement of fact. The equals sign (=) tells us a fact: that the difference between calories in and calories out has to be accounted for by the change in internal energy.
So, if we increase calories in and keep calories out constant, then the change in internal energy must increase by the same amount.
Similarly, if we increase calories out and keep calories in constant, then change in internal energy must decrease by the same amount.
Now, here's the important question:
How do we use this equation to create the change that we want to make happen?
That is, if we want to lose weight (a negative change in internal energy), how do we manipulate the other variables to create this change?
We could:
- Decrease calories in (eat less)
- Increase calories out (exercise more)
Is that it? Is that the magical step?
If you want to manage your weight, just think about eating less and exercising more?
We'll talk about that up next!