Calories In Calories Out Effect on Fat Loss & Muscle

importance of calorie counting

Table of Contents

After reading the ultimate guide to counting calories you should be able to understand what calories are, their importance in a diet and how to go about counting or estimating them. Now, if you are still confused as far as why calories are directly related to your goals that you identified in the identifying goals article, read along, you will see the relationship between the two as clear as the sun.
Regardless of any lies or misconceptions you have been fed while reading a fitness magazine, calories are the number 1 factor in creating a successful diet plan. While many other crucial factors exist, they merely build off caloric intake. No other dietary factory influences body composition as much as calories do. And that is a fact! It’s not super foods, it’s not drinking 2 cups of lemon juice a day, it’s calories!
In fact, calories are what’s mainly affected by your fitness goal(s). In other words, while macronutrients (carbohydrates, protein, fat) still affect your body composition, they are just set percentages of your total daily caloric intake. Those percentages will change slightly based on different scenarios on goals, but not to the same degree calories will change. Calories are the main difference between different dietary goals.
Still confused? No problem! Let’s explain some basic concepts first to see why and how your calorie intake will be affected by your goal(s)

Caloric intake (calories in)

Every single food or beverage contains energy (calories). The only exception to this rule is obvious foods/liquids like water. Otherwise, almost everything contains energy. I said almost, because some foods like herbs and artificial sweeteners contain negligible amount of calories that they can be considered calorie-free.
Thus, whenever we eat or drink something, we acquire energy -energy intake-. This is commonly referred to as calories in.

Caloric expenditure (calories out)

As I have explained in the ultimate guide to count calories, everything we do or “don’t do” requires energy. Our bodies get use calories (energy) to keep us alive, perform bodily functions, perform cellular reaction, provide energy for us to run, walk…etc.
In fact, even if you were to just sit still for a whole day without doing anything, your body would still use a significant amount of energy (calories) to perform its daily functions. So, when we train, walk, work, jump or do any type of physical activity, we use even more energy.
Since calories are what the body uses to fuel its activities, this is commonly referred to as calories out or caloric expenditure.

Okay, and?

Although I explained what calories in and calories out are in my guide to count calories, it is important to reinforce those critical concepts because they will serve as the backbone of understanding what happens next.
Let’s review some quick concepts from the last article:
Calories in > calories out = caloric surplus
Calories in < calories out = caloric deficit
Calories in = calories out = maintenance / caloric maintenance
While is generally what happens to your body under different scenarios of caloric intake and expenditure, this doesn’t tell you the whole story. So, what happens during each one of those different scenarios?

Caloric Surplus
calorie surplus
When you are in a state of a caloric surplus, you are taking in more energy than you are burning. Since the 1st law of thermodynamics states that the extra energy must go somewhere, those extra calories you ate will be either stored as fat, muscle or most likely both.
In other words, you either ate more than your body needs and your body has to deal with those extra calories. Your body cannot just get rid of precious energy like that. The human is designed for survival, and thus it would NEVER waste excess energy, however, it stores it for when the famine hits.
So, what determines those different outcomes? 
Simple, a stimulus! If you are lifting weights, you will be creating microscopic tears in your muscle tissue. Now, given that you are taking in extra energy that your body will have to store for later use, your body will then use those calories to repair the damage caused by weightlifting causing your muscles to grow back bigger and stronger.
Thus, the equation is as follows:
Muscle Stimuli (weightlifting) + excess calories (more than your body needs) = You gain muscle. Yay!
However, in the absence of a training regimen (stimulus), your body will just then take those extra calories, convert them into fatty acids and store them somewhere under your skin for later use. Why would it waste precious energy when it can use it during times of lack of food?
Thus, the fat equation is as follows:
Excess calories (more than your body needs) + NO EXERCISE (stimulus) = You gain fat. BOO!
Now, it’s not all clear and cut like that. In almost all cases, you the outcome will be a combination of the above two scenarios. The ratio of muscle to fat that you gain will largely depend on the size of your caloric surplus, how good your training program is, the ratios of macronutrients you are consuming and, of course, your genetics.
If you eat too much (Very large caloric surplus), most of those extra calories will be stored as fat and very little will be stored as muscle.
If you eat the right number of extra calories to support myogenesis (muscle growth), most of those calories will be used to build muscle and very little will be stored as fat.
Don’t worry, those details will be discussed later.
So, what should you keep in mind?
#1 The number 1 factor of building muscle is eating the right number of extra calories to support muscle growth.
Moving on, let’s explore the second scenario.

Caloric Deficit
calories thermodynamics
A caloric deficit as you should know by now is when you consume less calories than your body needs. So, if your body needs 2000 calories every day to keep you alive, and you only eat 1500 calories, you created a caloric deficit. Your body will then compensate for the lack of energy intake and find alternative source. In this example, your body will then burn 500 calories from previously stored energy on your body. However, that energy can come from two difference sources; Muscle, fat. And of course, a combination of the two.
Body fat: 
People who lose a good amount of weight create a caloric deficit by either increasing their activity level so that they expend more calories than they take in, or they eat less calories than their body requires. There is no other way around it. You keep a caloric deficit for a good amount of time and your body keeps using the stored body fat as energy, hence, you lose fat/weight.
Lean muscle tissue:
Your body can also convert muscle tissue to energy and use that as its alternative energy source. In fact, your body prefers to break down muscle tissue to use as energy because it’s not an extensive process like fat breakdown. This is not what we want.
You are smart enough to know that you want your body to get that needed energy from fat as opposed to hard-earned muscle tissue.
Once again, and depending on many factors, your body will use both stored body fat and lean muscle tissue to make up for the lack of energy intake. This is largely dependent on many details that we can luckily manipulate, except for genetics (BOO).
So, what determines those different outcomes?
Just like being in a caloric surplus, the outcome depends on muscle stimuli and how large your deficit is.
If you eat too little and you create a large caloric deficit to lose weight fast, most of the weight you shed will come from muscle break down and very little will come from stored body fat.
This is especially true in the absence of a muscle stimulus.
So, here are two quick equations:
Muscle stimulus + very large caloric deficit = most lost weight comes from muscle breakdown.
No muscle stimulus + caloric deficit (whether large or moderate) = most lost weight comes from muscle tissue.
However, if you create a moderate caloric deficit and provide strong consistent muscle stimuli, majority of the energy compensation will come from ugly stored body fat.
An equation a day keeps the doctor away:
Strong and consistent muscle stimuli + moderate caloric deficit = majority of lost weight will be in the form of body fat. Yay!
#2 The number 1 factor of losing fat is to create a moderate caloric deficit and exercise consistently.
#3) If you want to lose weight regardless whether it comes from fat, muscle or both, you just need to create a caloric deficit.
This leads us to the third and last scenario.

Caloric balance (calories in = calories out)
Since we can physically be in a caloric surplus or a caloric deficit, we can logically be in a state of caloric balance. When you consume the same number of calories your body burns, you maintain your weight. This occurs because your body doesn’t have any extra energy to store and it doesn’t have to use your stored body fat or lean tissue as fuel since it’s already getting the needed amount of energy.
Important: Many fitness enthusiasts and figures argue that when you are in a caloric balance, you don’t affect your body composition negatively or positively. This is FALSE! Yes, you will most likely maintain your weight, however, if you train right and provide necessary nutrients and macros to your body, your body will build muscle and burn fat simultaneously, or recomp like we said in the past article. Recomping is a bit slower than “bulking” and “cutting”, however, body transformations do not happen overnight, it’s a marathon not a race! Recomping is usually the best solution for “skinny fat” people who need to gain some muscle mass and lose the annoying layer of fat they have had for the past decade or so. How do I know that recomping is doable? I have done it! I will post an article explaining my recomping journey at a later time. But due to many physiological processes such as protein synthesis, lipolysis and many others, our bodies constantly either burn fat or build muscle. Details will be in the recomping article, don’t worry.
But if you would also like some scientific data to back up my claim, have a look at just this study (there are literally dozens of studies out there concluding the same thing. Google Scholar is your friend).
Another point: Building muscle while in a caloric deficit is possible. Burning fat while in a caloric surplus is also possible. Just take my word on it till we get to those subjects.
But if you are impatient, like me, and want to read a bit more about this holy grail of fitness training, read this article at Bayesian Bodybuilding by the fantastic fitness model and scientific researcher, Menno Henselman who has a tremendous understanding of this subject:

Can you gain muscle and lose fat at the same time?

For now, let’s agree that when your calories in = calories out you maintain your WEIGHT (not body composition).

What’s next?
By now, you should understand the importance calories play in an effective diet and how they can affect your goals. Everything that is to come will be built using your maintenance calories.
So, let’s learn how to calculate your maintenance calories (your daily caloric requirements).

Calculating your daily calorie requirements



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