By Skyler Zarndt MS, ATC, CSCS
The First Law of Thermodynamics is a version of the law of conservation of energy. It basically states that energy cannot be created nor destroyed. It can be transferred from one form to another, but the total energy of an isolated system remains constant.
This is essentially how we were taught to think about nutrition. If we eat less and exercise more, than we will lose weight (or change our body composition). If we eat more and are sedentary, we will surely get fat.
We can essentially define this idea through this equation:
Change in Fat Mass = Energy Consumed – Energy Expended
A set number of calories consumed, minus the energy we expend throughout the day. This should put us in a NEGATIVE caloric balance, and we should lose weight.
The idea of this post is to discuss the idea that calories ARE NOT created equally. We all know the energy breakdown for the 3 macronutrients:
- Fat: 9 kcal/gram
- Carbohydrate: 4 kcal/gram
- Protein: 4 kcal/gram
Pretty simple so far, right? Fat provides the most “energy” per gram, while carbohydrates and protein are equal at 4 kcal/gram. So, it makes sense that we should stay away from fat’s.
If you’re still applying the 1st Law of Thermodynamics, and we need to consume less calories and burn more to lose weight, then eating fat’s just seems silly! And if we want to LOSE fat, then why should we EAT fat?! That’s completely counter-intuitive!
Not so fast.
The equation above doesn’t necessarily tell us WHY this equation makes sense. There is no arrow of causality. The law certainly works for physics, but not for biology. And lasts time I checked, human’s are BIOLOGICAL organisms.
We are taught to BALANCE our food intake with our activity level. Of course this sounds like a good idea. 2000 calories a day in, 2000 calories a day burned throughout the day, no weight gain ever!
But it’s also unrealistic.
As Gary Taube’s, author of Why We Get Fat: And What to Do About It, would say, “practicing energy balance is impossible.”
To put this into perspective, let’s get into a little bit of math.
As Taube’s broke down in one of his lectures (which I’ll link at the end of the post), let’s assume that we do count our calories and try to match it with our energy expenditure. We know our Basal Metabolic Rate (BMR), we know how many calories we burn during exercise, and we track EVERYTHING that goes into our diet.
Now let’s also assume that we ACCIDENTALLY over-consume by a mere 20 calories per day. 20 calories isn’t much. Lets look at few things that might equal 20 calories.
- 1/3 of a small orange
- 2 animal crackers
- 1/3 of a small banana
- 4 cherries
- 1/8 cup of apple juice
So those are just a few examples to demonstrate that eating 20 extra calories a day would most likely go unnoticed. That type of precision is VERY difficult.
On the assumption that we overeat by 20 calories everyday, here’s the math to determine our weight gain over the course of say, a decade.
(20 kcalories x 365 days x 10 years) / 3500 (calories in 1 pound) = 21 lbs in a decade.
42 pounds in 20 years (this would make most of us “obese”)
Now the interesting thing, to me, is not the amount of weight gained throughout the years (although a mere 20 calories excess a day can do that), but the PRECISION that is required to regulate weight.
I’m terrible at math and avoid it when I can. As a strength coach, I count by 10, 25, and 45 pretty well. That’s it. Always addition or subtraction. So why would I want to try to MANAGE my calories on a daily basis with such great accuracy? I couldn’t!
Do animal’s use this equation? Do you think they are familiar with the laws of thermodynamics? I’m guessing no, too. Yet somehow they manage to maintain normal weight! (Minus the occasional overweight house pet!)
That tells me that there has to be something going on within the body that does the “counting” for us. And when I say counting, I mean REGULATING how our calories are “spent.”
This leads us into how calories are NOT created equally. In its simplest form, it’s the idea that carbohydrates, fats, and proteins all have DIFFERENT effects on the body. The body uses each macronutrient differently. And if we aren’t careful, we can throw our body completely out-of-whack if we don’t take into consideration the effects of each.
In Part 2, let’s take a look at the macronutrients, fat in particular, and the effects it has on the human body. We’ll talk about why eating fat DOESN’T make us fat, and why the “food pyramid” is wrong!
Photos Courtesy of: