Calories In vs Calories Out

Calories In vs Calories Out

Is losing or gaining weight as simple as calories in versus calories out?

The answer is yes.

And no.

But mostly yes.

Now let me explain.


 The First Law of Thermodynamics


So to begin with some background on this topic, I will dive into my inner engineering nerdy ways. Many people proclaim that calories in equals calories out via the first law of thermodynamics. This law, in a simplified meaning, states that energy cannot be created nor destroyed but transferred from one state to another. Confused? Good, let me explain some more.

If you eat 2,000 calories in one day and throughout your daily activities burn 1,800 calories, you will gain weight.

2,000 Calories In – 1,800 Calories Out = +200 Net Calories

These excess calories cannot magically disappear and have to go somewhere (i.e. gain weight). Vice versa, if you eat 1,800 calories and throughout your daily activities burn 2,000 calories, you will lose weight.

1,800 Calories In – 2,000 Calories Out = -200 Net Calories

The lack of calories needed to maintain equilibrium causes your body to take away from its energy storage (i.e. lose weight).

So this makes since, right? Then where does the “no” come from?


Food for Thought


Let’s say I want to start a new trend and lose weight while eating Twinkies, ice cream, and fried chicken. If I only eat these three food items and have consistent negative daily calorie intakes, I will lose weight. So why not start the new fad of the Twinkies, ice cream, and fried chicken nutrition plan? Because it lacks what nutrition plans are supposed to provide………..nutrition.

The one flaw for calories in and calories out is that it doesn’t account for what the body itself needs. Calories are a form of fuel for the body, but with food come vitamins, minerals and fiber. These three main micro-nutrients keep the body functioning properly and diseases/sicknesses at bay.

Also, let’s take a look at this quick thought experiment. If everyone ate the same amount of calories from the same foods and burned the same amount of calories daily, would everyone look alike? And that answer is no. One aspect that the first law of thermodynamics doesn’t account for is differences in genetic makeup. Metabolisms will alter from person to person and how everyone reacts to certain foods will differ (i.e. insulin). It’s not that the first law is flawed; it’s just irrelevant in this situation.


Lettuce Wrap It Up


Let’s look at the results from a study graphed below from (sorry about the blurry graph but its all I could find on the topic at hand).

This graph shows that there is a correlation with consistently monitoring calories and weight loss. Controlling your weight relies on your awareness of calorie intake and having healthy eating habits.

So what to do? Eat smaller portioned meals that are very “clean” and rich in vitamins, minerals, and fiber (Fun fact: average meal portions today are four times larger than they were in the 1950s). If you’re up to it, track your calories for optimal results using the MyFitnessPal app. There will be more posts to come on details of tracking calories in future blogs. Hope you enjoyed this post and don’t forget to like, comment, share, and subscribe!


“You are what you eat.” 


Book of the Month:                                               “Shoe Dog” by Phil Knight


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