Despite the claims of various misinformed people, diet cults, pseudoscientific nutjobs and the countless “experts” willing to say whatever is needed to make money selling you bullshit, calories are the most important part of your diet.
Whether you want to lose weight, gain muscle or simply maintain your current weight, how many calories you eat a day is always going to be the key determining factor.
No, it’s not the only thing that ever matters. It’s simply the thing that always matters most.
And it’s this fact that often leads to the following questions:
- Why do calories matter so much?
- What is the best way to calculate my calorie needs?
- How many calories should I eat a day to lose weight?
- How many calories should I eat a day to gain muscle?
Let’s now answer all of these questions, starting at the top…
Calories In vs Calories Out
The reason why your calorie intake is the most important part of your diet comes down to a very simple and scientifically proven concept best summed up as “calories in vs calories out.”
Here’s how it works…
- Calories In
This refers to all of the calories you “take in” each day via the foods you eat and the drinks you drink. For the most part, everything you consume (except stuff like water and other zero calorie drinks) contains some number of calories. (No, there are no “negative calories foods.”)
- Calories Out
This refers to all of the calories you burn each day. This includes calories burned during traditional forms of exercise (weight training, cardio, etc.) as well as normal daily movement (standing, sitting, walking to your car, brushing your teeth, etc.), spontaneous daily movement (fidgeting, adjusting your posture, etc.) and all of the “behind the scenes” activity taking place to keep you alive and functioning (pumping blood, digesting food, breathing, etc.).
With this in mind, there are 3 possible scenarios that can take place…
Scenario #1: Caloric Surplus
When you consume more calories than you burn (i.e. “calories in” is greater than “calories out”), you have what’s known as a caloric surplus.
This means there are leftover calories that never got used for anything, and they now have to go… somewhere. They can’t just disappear into thin air. Rather, your body will be forced to store them somewhere in itself for potential later use.
As it turns out, there are 2 storage options available within your body: fat cells and muscle tissue.
This is why a caloric surplus will always cause you to gain something. Either body fat, muscle mass, or a combination of both.
Now, in some very specific cases when a person is properly training/eating for the purpose of gaining muscle (more about that later), the ideal outcome is for most of those surplus calories to be stored in the form of muscle. However, in all other cases – meaning the vast majority of the time – a caloric surplus is going to result in fat being gained.
This is, after all, the one and only way that fat is EVER gained. So, if you or any other human on the planet has ever gained a single pound of fat, this is always what caused it. You consumed more calories than you burned (aka a surplus) and the excess was stored in the form of body fat.
Now for the opposite scenario…
Scenario #2: Caloric Deficit
When your body burns more calories than you consume (i.e. “calories out” is greater than “calories in”), you have what’s known as a caloric deficit.
This means that you didn’t consume enough calories to support the energy needs of your body. Rather, your body needed some number of calories to burn in order to do all of the stuff we mentioned earlier, and you consumed some degree less than this.
When this happens, your body is forced to find some alternative fuel source to burn for energy instead. After all, new energy cannot just be created out of thin air. It has to come from somewhere.
As it turns out, there are 2 fuel sources available within your body where leftover energy has been stored in preparation for this very scenario: fat cells and muscle tissue.
This is why a caloric deficit will always cause you to lose something. Either body fat, muscle mass, or a combination of both.
As you can already guess, in the vast majority of cases, a caloric deficit will primarily result in fat being lost. Yes, even when people screw up various aspects of their diet and workout and therefore end up losing muscle along with fat (something you want to minimize as much as possible), fat will almost always continue to make up the majority of what’s being lost.
This is, after all, the one and only way that fat is EVER lost. So, if you or any other human on the planet has ever lost a single pound of fat, this is always what caused it. You consumed fewer calories than your body needed to burn (aka a deficit), which lead to stored body fat being burned for energy instead.
Now for the final scenario…
Scenario #3: Maintenance
When you consume the same number of calories that you burn (i.e. “calories in” is equal to “calories out”), you’re at what’s known as a maintenance.
Since there is no surplus that needs to be stored anywhere, and no deficit that warrants burning off a backup fuel source, what happens is that you don’t lose or gain anything. Rather, you simply maintain your current state.
Now I know what you’re probably thinking…
“I don’t want to maintain my current state bro, I want to improve it! Let’s skip this section and get to the good stuff.”
I hear ya. But here’s the thing. This “maintenance” scenario is the one that’s going to help you figure out exactly how many calories you should eat a day to lose weight or gain muscle.
- Because being “below maintenance” will constitute being in a caloric deficit… which is needed for weight loss to happen.
- And being “above maintenance” will constitute being in a caloric surplus… which is needed for muscle to be gained (in most cases, at least).
And that brings us to a very obvious question: what the hell is this “maintenance” amount that you need to be below or above?
How To Calculate Your Maintenance Level
Have you ever come across the phrase Total Daily Energy Expenditure (TDEE)?
It’s basically a much fancier term for your maintenance level, as it represents the TOTAL amount of calories your body burns each day doing EVERYTHING.
- Basal Metabolic Rate: This is the amount of calories your body burns at rest just keeping you alive and functioning. So, imagine the number of calories you’d burn if you stayed in bed all day not moving (or digesting food).
- Thermic Effect of Activity (TEA): This is the calories your body burns each day via exercise.
- Thermic Effect of Food (TEF): This is the calories your body burns during the digestion and absorption process of the foods you eat
- Non-Exercise Activity Thermogenesis (NEAT): This is the calories burned as a result of all of the little things you do over the course of the day BESIDES exercise… which includes unconscious, spontaneous daily movement (i.e., the seemingly minor movements you make throughout the day that you didn’t consciously plan to make). This actually accounts for a surprisingly significant amount of the calories that people burn each day.
And all of this stuff varies from one person to the next. Hell, even when people are the same gender, height, weight and age, and they’re doing the same amount of exercise, you can still see huge variances in TDEE thanks to NEAT alone.
For this reason, it’s virtually impossible to tell you exactly what your maintenance level/TDEE is. Instead, the best we can really do here is come up with an estimated maintenance level.
Don’t worry though, this is fine. As you’ll soon find out, an estimated starting point is all we truly need.
And that brings us to our next obvious question: how do we calculate it?
The Maintenance Level/TDEE Calculation
There are dozens of different methods, equations, formulas and calculators to use for this, some of which are more or less complicated than others and often more or less accurate as well. In fact, a method that is super accurate for one person can be extremely inaccurate for another.
That’s why I often recommend just using the quickest and simplest method possible. It tends to be accurate enough and, when you compare the various methods, you’ll often find that they all fall within a similar range anyway.
So, here’s what I recommend…
Body Weight (LBS) x 12-18
Take your current body weight in pounds and multiply it by 12 and 18.
Most people will find that their maintenance level falls somewhere in between those two amounts (most often between 14-16).
For example, a 200lb person would do 200 x 12 and 200 x 18 and get an estimated daily maintenance level of somewhere between 2400-3600 calories.
Those who are female or less active both in terms of their job/overall lifestyle and how much exercise they do should usually stick more toward the lower half of their estimate. Those who are male or more active should usually stick more toward the upper half of their estimate. If you’re unsure, just pick a number somewhere in the middle.
Got it? Good.
Now that you have your estimated maintenance level, it’s time for the step you’ve been waiting for: determining exactly how many calories you should eat a day to lose weight or gain muscle.
Let’s start with losing weight…
How Many Calories A Day To Lose Weight?
As I explained earlier, a caloric deficit is the sole cause and requirement of fat loss. Which means, if your goal is to lose weight… your #1 focus must be to ensure that you are consistently below your maintenance level so that a deficit exists.
The only question is, what size should that deficit be? How far below maintenance should you go? Here’s what I recommend:
The ideal caloric deficit for most people is somewhere between 10-25% below their maintenance level. (Whenever in doubt, an even 20% is often a fine starting point.)
While there are certain rarer cases where something below or above this recommended range might be ideal, this tends to be the sweet spot for the vast majority of the population. This is because it will typically cause a rate of weight loss somewhere between 0.5-2lbs per week. For most people, this is ideal.
Here’s how it works…
Let’s pretend some example person had a maintenance level of 2500 calories. If they were to then create a deficit of 20%, they’d figure out that 20% of 2500 is 500. They’d then subtract 500 from 2500 and get 2000. In this example, this person would eat 2000 calories a day to lose weight.
Now let’s answer 2 questions that may have just popped into your head…
1. Where In This Range Should I Be?
At this point, you’re probably wondering what determines whether you should create a 10% deficit, a 25% deficit, something in between (like the 20% used in our example), or something below or above this range altogether?
Good question, and I have two answers to it…
The Shorter Answer
Simply put, the faster you want to lose, the larger the deficit should be. The slower you want to lose, the smaller the deficit should be.
But at the same time, the larger your deficit is (and the faster you’re therefore losing), the harder it tends to be because various hormonal and metabolic factors are affected to a larger degree (plus a larger deficit warrants making the biggest changes to your diet and/or workout).
And the smaller your deficit is (and the slower you’re therefore losing), the easier it tends to be because those same hormonal/metabolic factors are affected to a lesser degree (plus a smaller deficit warrants making much smaller diet/workout changes).
In addition, smaller deficits tend to be more ideal for people who don’t have much fat left to lose and/or those who are looking to go from lean to really lean. Larger deficits tend to be more ideal for people with a lot of weight to lose, partly because someone with more weight to lose usually should lose it faster than someone with less to lose, and partly because those hormonal/metabolic issues aren’t as problematic at higher body fat percentages.
And of course, you have your own personal needs and preferences to consider as well. As in… do you simply want or need to lose weight faster or slower?
So… yeah. There are pros and cons to every deficit size, and quite a few factors to take into account.
The Better Answer
This is why I spent an entire chapter answering this question in Superior Fat Loss.
In it, I clearly break down ALL of the pros and cons of EVERY possible deficit size to show you exactly what your ideal rate of weight loss is and exactly what size your deficit should be for getting the best combination of A) realistically fast fat loss, B) minimizing all of those hormonal and metabolic issues (and everything else that makes losing weight so hard) so things are as easy and sustainable for you as possible, and C) maintaining muscle while that fat is lost.
You can learn all about it right here: Superior Fat Loss
2. Where Does Exercise Fit Into This?
That’s entirely up to you. Why? Because exercise – specifically the kind being done for the purpose of burning calories/causing weight loss – is completely optional.
That’s because there are 3 different ways you can create your deficit…
- Diet (eating fewer calories)
- Exercise (burning more calories)
- Diet + Exercise (doing some combination of both)
So, using our same example from before, this person could potentially eat 2000 calories a day, or eat 2500 calories a day and then burn 500 through some form of exercise, or eat 2250 and burn 250, or anything similar.
In all 3 cases (and with all else being equal), they end up with the same 500 calorie deficit and will therefore lose the same amount of weight.
So… which method should you use to create your deficit? That’s entirely up to you and your own preferences.
Basically, whichever method is most doable and sustainable for you, that’s how you should do it. I cover this topic in much more detail here: How Much Cardio To Lose Weight and What Is The Best Way To Lose Weight
Now for goal #2…
How Many Calories A Day To Gain Muscle?
As I explained earlier, a caloric surplus is a requirement for gaining muscle in most cases.
Yes, there are some exceptions (most notably fat beginners) where stored body fat can be converted into the extra energy needed to synthesize new muscle tissue. But, for the most part, anyone looking to gain a meaningful amount of muscle at an acceptable rate will need additional calories via their diet to make it happen.
Which means, if your goal is to gain muscle… you’re #1 dietary focus should be to ensure that you are consistently above your maintenance level so that a surplus exists.
The only question is, what size should that surplus be? How far above maintenance should you go? Here’s what I recommend:
MEN: create a daily surplus of about 200 calories above your maintenance level.
WOMEN: create a daily surplus of about 100 calories above your maintenance level.
Please note, however…
These Surplus Recommendations Are Averages
Meaning, the average man should aim to gain between 1-2lbs per month. The average woman should aim to gain between 0.5-1lb per month. On average, this tends to be the sweet spot for maximizing muscle growth and minimizing fat gains, and, on average, these are the caloric surplus recommendations that will make it happen.
Can you tell that I’m going slightly out of my way to emphasize the word “average” here?
Good. Because there are actually MANY cases where a smaller or larger surplus will be ideal based on factors specific to each person that can affect their potential rate of muscle growth. This includes their age, experience level and a variety of genetic factors.
Why does this matter, you ask? Two reasons:
- Too small of a surplus can prevent or minimize muscle growth.
- Too large of a surplus will lead to excessive amounts of body fat being gained.
This is why I spent an entire chapter in Superior Muscle Growth breaking down every single one of these individual factors to provide you with specific surplus recommendations that are ideal for different categories of people. Male or female. Younger or older. Beginner, intermediate or advanced. Good genetics, average genetics and bad genetics. And so on.
You can learn all about it right here: Superior Muscle Growth
But sticking with the average recommendations I gave above, here’s an example of how it would work…
Let’s pretend some example person had a maintenance level of 2000 calories. If they are male, they should eat 2200 calories a day to gain muscle. If they are female, they should eat 2100 calories a day to gain muscle.
The Most Important Step Of All
Right now you have a number in mind for how many calories you should eat a day to lose weight or gain muscle.
And as nice as that number may be, it’s crucial to remember that it is just an estimate.
The maintenance level you calculated? Just an estimate. The ideal deficit for you? Also just an estimate. The ideal surplus for you? Again, just an estimate.
So while it would certainly be nice if this calorie intake turned out to be the 100% completely perfect calorie intake you need it to be, there’s a chance that it won’t.
That’s the bad news.
The good news, however, is that there is a very easy solution to this problem.
It’s something I like to refer to as The Key Step.
The Key Step
- Weigh yourself every day – first thing in the morning before eating or drinking – and take the average at the end of the week. (Additional details here: When Is The Best Time To Weigh Yourself)
- Pay attention to the weekly averages (not the meaningless daily fluctuations) for a period of 2-4 consecutive weeks.
- Ask yourself the following question: is my weight moving in the right direction at the ideal rate it should be?
- If the answer is yes, you’re all good. Keep eating this amount of calories each day and continue monitoring progress. If the answer is no, then adjust that calorie intake up or down in small increments (e.g. 100-300 calories at a time), wait another 2-4 weeks and see what happens then. Is your weight moving in the right direction at the ideal rate it should be? If so, you’re good. If not, adjust again and repeat this process until it is.
All of the maintenance level estimates, calculators and deficit/surplus recommendations in the world are lovely and wonderful, BUT THIS IS THE KEY STEP to guaranteeing that you’re eating the right amount of calories a day. Additional details here: Which BMR/TDEE Calculator Is Best?
Summing It Up
So, how many calories should you eat a day to lose weight or gain muscle? It’s pretty easy.
- Start by estimating your maintenance level.
- From there, create your deficit or surplus depending on which one suits your goal.
- And finally, monitor your progress and adjust when/if needed.
When your body weight is moving in the right direction at the ideal rate it should be, you’ll know you’ve found your ideal calorie intake.
Now that your daily calorie intake has been figured out, the next thing you’re probably going to want to do is figure out what your daily protein, fat and carb intake should be.
To do that, just follow the 5 simple steps I explain right here: How To Calculate Your Macros