How Many Calories Should I Eat to Gain Muscle?

calories to build muscle

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So, you want to gain some muscle, ha? Perhaps you just want to gain weight (fat, water and muscle) because you are anorexic or want improve your health and prevent a potential medical condition. If so, you are at the right place! The reason why gaining muscle and gaining weight are combined in one article as opposed to losing weight and losing fat is that the mechanisms used to gain muscle are the same as the mechanisms responsible for gaining weight.

Important notes:

  • I don’t recommend mindlessly gaining weight. Ideally, you want to gain weight in the form of muscle, not fat. However, gaining weight is a good goal to aim for if you are severely underweight and want to improve your health. But, you still don’t want to gain too much fat. This will be counterproductive for your aesthetic appearance and overall health.
  • If you gain muscle you will look better, improve your health, increase your metabolic rate and improve your athletic performance.
  • If you gain weight, you will be gaining mostly fat, water and maybe some lean body mass.

If you have been reading this guide from the beginning, I’ll assume you know the following:

  • If you want to gain muscle or weight you need to eat a caloric surplus.
  • A caloric surplus is when you eat MORE calories than you burn per day. Your body will then store that extra energy in the form of fat or muscle. You cannot gain muscle or weight out of nothing. Thus, you need building blocks (nutrients, vitamins…etc.) and energy and both will come from an overflow of calories.
  • Gaining muscle or gaining weight is an energy-demanding process. Thus, while your body can indeed gain muscle/fat in a caloric deficit, the rate at which your body does will be much slower in comparison to being at a caloric surplus.
  • You should know what your daily caloric requirements are. 

So, you know your daily caloric requirements, how many calories do you need to eat to gain weight or gain muscle at as fast as possible? First, let’s discuss gaining weight since it’s easier. 

Gaining weight fast

Keep in mind that gaining weight (fat) is NOT ideal or recommended. But if your goal is to gain weight, this is what you want to do:

  • Gain weight FAST.
  • You don’t want to gain too much weight! Perhaps you have a specific number of pounds that you want/need to gain.
  • Do it all in a safe manner.
  • Do it in a convenient way. 

Just like we have types/sizes of caloric deficits, a caloric surplus can come in different sizes; small, moderate, large. Each surplus size has its advantages and disadvantages. For the goal of gaining weight rapidly, I recommend we start off with a moderate caloric surplus.
Even if you are severely underweight, I recommend you use a moderate a caloric surplus in the beginning. If you feel like you need to gain weight faster, you can always adapt a large caloric surplus.

Here is why I think a moderate caloric surplus is the best:

  • You will gain weight at a moderate pace. Thus, you won’t accidentally gain too much weight. This will prevent from feeling like you need to lose weight later and thus will prevent a yo-yo type effect.
  • Even if you are anorexic, you will still be gaining weight. Thus, your health markers will improve as you consistently gain weight.
  • You will be able to control the rate at which you gain weight easier.
  • Gaining weight will occur at a faster rate than if you were to utilize a small caloric surplus. This will encourage you to keep going till you hit your target goal.
  • If you utilize a very large caloric surplus and start eating too much, some of your bodily functions may start to get thrown off balance, which will be counterproductive. For instance, you may become insulin resistant due to too much carbohydrates. Your leptin and ghrelin levels will also take a hit. Your digestive system, metabolic efficiency and nutrient partitioning could take a hit as well.
  • Making constant progress will hopefully encourage you to start lifting some weights. If you are still sold on strength training, do yourself a favor and read this post:

Benefits of strength training

So, how many calories should you eat to gain weight fast?

The ideal caloric surplus to gain weight fast = 25% above daily caloric requirements.

This is true for both men and women. But, what does this mean?
This means that you need to eat more than your maintenance calories by about 25% of that number.


Stephen has a daily caloric requirement of 2500 calories per day. Stephen wants to gain weight so he decides to eat at a 25% surplus.
Stephen would then eat; 2500 + (0.25 * 2500) = 2500 + 625 = 3125 calories per day!

You may have failed your mathematics class, but this should be easy to figure out.
So, if your daily caloric requirements are 3000 kcals (calories) per day, you should then eat 3000 + 750 = 3750 calories per day.

How many pounds are we talking about here?

Extremely underweight individuals who want to gain 40 or more pounds should aim for 4-5 pounds per week.

Individuals who are that underweight will do much better gaining weight at that rate than if they were to gain weight slower. This will have a positive impact on their health and will allow them to manipulate things accordingly in case they choose to gain weight slower. Keep in mind that this is not sustainable and your metabolic rate, insulin sensitivity…etc. will take a hit after a while.

And since you are not doing any form of physical exercise (preferably strength training), 90% of those 4-5 pounds you gain will be in the form of fat. Some will be water and very little will be lean body mass. You will also hit a plateau at some point, but this will be discussed at the end of this article. And you will need to eat A LOT!

People who want to gain 20-40 to lose weight at a slower rate. This rate is equivalent to 2-3 pounds per week.

Gaining only 2-3 pounds per week will allow those individuals to put on weight in a timely manner without going over their target goal. This rate will also be sustainable and won’t affect bodily functions by much, or at least in the beginning.

If you only have 10-20 pounds to gain, you should aim to gain only 1-2 pounds per week.

Those individuals are not underweight, but just want to gain a bit of weight for health reasons, acting roles or God knows what else. Thus, a slower approach will be more ideal. If you decide to gain weight faster than this rate, you will most likely go over your target number of pounds. So, a faster approach is not recommended.

It’s very possible that as you make progress, you will move from one category to another. For instance, if an underweight individual has a target goal of gaining 40 pounds, he would then opt-in for a fast rate of weight gain. Few weeks go by and he manages to gain 20 pounds out of 40, he would then take a slower approach and eats to gain only 2-3 pounds per week.  That individual then gains 10 more pounds and he reaches a total of 30 pounds out of 40, he could then start gaining weight at an even slower rate of 1-2 pounds so he doesn’t go over his target pounds and gives his body a chance to optimize itself again and adapt to the new weight.

How can we gain a specific number of pounds?

In the ultimate guide to count calories easily and how many calories should I eat to lose weight articles I explained how you can manage to lose a specific number of pounds, right? Read those articles or at least one of them because gaining a specific number of weight works pretty much the opposite way.

Still confused? Let me explain.

Remember that one pound of body weight = 3500 calories

What does this mean?

So, if you want to gain one pound of body weight, you must eat a total caloric surplus of 3500 calories.


Jonathan wants to gain 5 pounds over the next 5 weeks, which means he wants to gain to one pound every week. Jonathan would need to take these measures:

  • Calculate his maintenance calories. Let’s assume his maintenance calories are 1500 calories.
  • Jonathan will create a caloric surplus that will add up to 3500 calories at the end of each week.
  • Thus, Jonathan would eat 2000 calories every day.
  • Jonathan eats at a caloric surplus of 500 calories per day so this add up to: 500 * 7 = 3500 calories by the 7th day.
  • Guess what happens? Jonathan gains one pound of body weight by the end of the week. Magical!

Jonathan is an indecisive guy and he wants to gain 3 pound per week instead! Damn Jonathan!

Jonathan would create a caloric surplus of 1500 calories per day so at the end each week he will have stored 1500* 7 = 10500 calories.

Given that 1 pound = 3500 calories. 10500 / 3500 = 3 pounds/week.


What’s next?

You decided that you want to gain weight, you set up your caloric surplus based on your preferred rate of weight gain and starting point.

Now, we want to ensure that we are gaining weight at the calculated rate. How do we go about doing that?

Just like the case in losing weight, you just need to start your journey. Start by weighing yourself because that will be your starting point then start eating at a caloric surplus. After that, start weighing yourself for a few weeks and track your progress to see whether the scale is moving or not and how much it is moving by.

One of these scenarios will happen:

You gain weight at the right rate: You choose to gain one pound per week. so, you create a caloric surplus of 500 calories per day so that your caloric surplus adds up to 3500 calories (one pound) at the end of the week. You then track your progress over the course of a week notice that you have gained exactly one pound. Congratulations! You do NOT need to change anything. Just stick with your plan and keep eating at that rate until your weight gain rate slows down significantly.

You gain MORE weight than you want: Let’s assume you want to gain two pounds per week instead of one. So, you create your caloric surplus and eat 1000 calories more than your maintenance calories per day so that by the end of the week you will have supplied your body with 1000 * 7 = 7000 calories more than your body needs (two pounds). You track your progress for a week and you gain pounds instead of 2. What happened? This means that you overestimated your maintenance calories and what you assumed was a 1000-calorie surplus was a 1500-calorie surplus. The calories added up and you gained 3 pounds instead of 2.

How to fix this?
your caloric intake by 250 calories per day and track your progress for another week. This simple adjustment should make you gain LESS weight than 3 pounds. If a week goes by and you’re still gaining weight faster than you should (let’s say 2.5 pounds instead of 2) then just decrease your caloric intake further and monitor your progress. That should do it!

You gain LESS weight than anticipated:

Let’s say you set up a caloric surplus of 500 calories per day to gain one pound per week. A week goes by, you step on the scale and you see that you gained only half a pound. Why? You, my friend, underestimated your maintenance calories and what you assumed was a 500-calorie surplus was just a 250-calorie surplus. Thus, you gained (250 * 7 = 1750 calories = 1/2 pound) only half a lbs. at the end of the week. Your daily caloric requirements were higher than you thought and thus the surplus was smaller.

How to fix this?
In case this occurs, just increase your calories by 250 calories per day and track your progress for another week. That should increase you rate of weight gain by another half a pound. If you only gained 0.75 pounds, just increase your calories by a couple hundred and track your progress. That should do it.

That concludes it for the folks who want to gain weight. Now, we will move on to those of you who want to gain muscle.

Eating to gain muscle

As much as we would all love to build muscle fast, it just doesn’t work that way. When you want to build muscle, there are two things you are aiming to do:

1- Gain muscle as fast as possible.
2- Gain as little fat as possible.

Gaining just pure muscle without gaining fat is impossible. However, maximizing muscle gain and minimizing fat gain is perfectly doable. The reason we cannot gain muscle without gaining fat is that there is a limit on how fast we can build muscle naturally. Many physiological functions are involved in storing excess calories as either fat or muscle, but when you gain weight, you gain both at the same time, but it’s the ratio of muscle gain to fat gain that matters. 

How can we maximize muscle gain while minimizing fat gain?

How fast someone gains muscle depends on many factors. Some are within our control and some are not. But, don’t give up, we definitely have control over this. Those factors include:

Insulin sensitivity – Nutrient partitioning. Individuals who are sensitive to insulin will experience better nutrient partitioning. Meaning their bodies will use most of the excess calories and nutrients to build muscle and very little will be used to gain fat.

Hormonal levels – Individuals with higher testosterone and growth hormone levels, like young males, will experience better muscle gains than individuals with sub-optimal hormones.

Myostatin levels – Myostatin is a protein that limits how much muscle someone can build naturally. This sets the muscle gain “ceiling”. Otherwise we would all walk around 250 lbs. shredded after 5 years of training. But no, there is a limit. Some individuals have lower myostatin levels naturally. Thus, they can build more muscle. But, don’t be jealous because that difference will not be that significant.

Caloric surplus size – In order for us to build muscle, we need a caloric surplus. Remember? Muscles will not be built out of thin air. Since there is a limit on how much muscle we can build naturally, then there must be an upper limit of how big our surplus should be.
Meaning that there is a certain number of extra calories you should consume above your maintenance calories to maximize muscle gain and minimize fat gain.

The ideal rate of muscle gain for men = 2 lbs. per month.
The ideal rate of muscle gain for women = 1 pound per month.

This rate translates into the following surplus:

Males – Eat at a 250-caloric surplus. So, if your maintenance calories are 2000 calories, eat 2250 calories every day so that you gain 0.5 lbs. per week.

Women – Eat at a 125-150 caloric surplus. If your daily caloric requirements are 1000 calories, eat 1125-1250 calories per day so that you gain 0.25 lbs. per week.

Now, don’t start eating more than that, otherwise you will be gaining more fat along with muscle. This is counterproductive because your newly gained muscle will be covered by an ugly layer of fat that you will attempt to lose later. Why the hassle? Just gain weight at a steady and slow rate and before you know it, you will have built an outstanding physique. This is a marathon, fellas!

What if I am not gaining weight at the right rate?

You see the section above where I talk about what to do if you are not gaining weight at the right pace? Same thing applies to muscle gain. Just increase or decrease your calories according to the situation.

Weight/Muscle GAIN Plateaus

After a while of gaining muscle or gaining weight, you may run into a plateau. That’s normal and expected. Weight gain plateaus are different than muscle gain plateaus. Let’s discuss weight gain plateaus first.

Weight gain plateaus

So, you have been eating at a caloric surplus for a while and suddenly you stop gaining weight. What happened? If you started at a weight of 120 lbs. and now you weigh 150 lbs., guess what? Your daily caloric requirements have changed! Now that you have 30 more pounds on your frame, your body requires more energy to supply those 30 extra pounds with. So, if your daily caloric requirement was 2500 calories at 120 lbs. and you were eating 3000 calories to gain 1 pound per week, your metabolic rate has increased and your maintenance calories are probably closer to 3000 calories now! In simple English, what was a caloric surplus to you at some point is now your maintenance calories. 

So, how can you fix this?

If you still want to gain more weight, simply recalculate your daily caloric requirements using your new weight and eat at caloric surplus again! That’s it. Voila! You will start gaining weight again.

Muscle gain plateaus

Muscle gain plateaus are harder to deal with due to several factors. Those factors include:

– Dietary changes.

– Changes to your training program.

We will discuss the first one. However, the second factor is outside this article’s scope. But, worry not, there will be a completely training design series and that specific subject will be discussed thoroughly. Stay tuned!

You have been eating the right caloric surplus (250 extra calories for men and 125-150 for women) and lifting weights to gain muscle. Things have been going perfect until suddenly your progress stalls. You attribute this to having a bad week at the gym or normal weight fluctuations. So, you keep at it for a few more weeks but your strength is not increasing, you are not seeing any visual changes in your physique and the scale is not moving. What happened? Once again, what happened is that your daily caloric requirements have increased. You start at 140 lbs. and you manage to gain 20 lbs. of muscle.

Congratulations! I have some news for you; your daily maintenance calories have increased due to the extra 20 lbs. you have gained. Your body requires more energy to sustain itself now. This is even more true when gaining muscle because muscle tissue demands more energy than adipose tissue (fat). So, when you gain muscle mass, your metabolic rate also increases!


you can either increase your calories by 250 calories at a time and monitor your progress for a couple weeks. Or you can recalculate your daily caloric requirements and add 250 to that number. Voila! You will start building muscle again.
Also, focus on eating quality foods, not junk. And sleep well!

What’s the next step?

If you made your way through this segment of this article, this means that you have an action plan to either gain weight or gain muscle. People who just want to gain weight can stop here and start enjoying those extra calories. You can also skip to the supplements chapter if you want to learn a bit more. However, for those of you whose goal is to gain muscle, feel free to head over to the macronutrients chapter and read the protein article.

What is protein? And why is it important?

You have now mastered creating your own customized diet plan to gain weight or muscle based on your goal, starting point and the rate you pick! 



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