A pound of muscle contains about 1,200 calories of stored energy (study, study). However, just like a mason spends energy laying stones, it also takes energy to construct that muscle, adding another 500–1,000 calories. And so, overall, it takes about 2,000 calories to build a pound of muscle (study).
Now, a mason can only lay so many stones in a day. Giving him more energy than he can use won’t help him lay those stones any faster. Instead, the extra calories will simply be saved for later. They’ll be stored as body fat. So, how many extra calories should you eat every day to maximize your rate of muscle growth?
To answer that question, we have to consider the hardgainer issue. Some people have more aggressive metabolisms than others. It might take 2,000 calories to build a pound of muscle on average, but it varies from about 1,500 to 2,500 calories, depending on the person. We’ll delve into that, too.
Estimating the Energy Cost of Building Muscle
Muscle is made of water (75%), protein (20%), and a mix of fat and glycogen (5%). Water weighs a lot, but it doesn’t contain any calories. Only the protein, fat, and glycogen can be broken down into energy. That’s why a pound of muscle only contains 1,200 calories, whereas a pound of fat contains 3,500 calories.
This is where people often make a mistake. They assume that since a pound of muscle contains 1,200 calories, it must take 1,200 calories to gain that pound. That’s not quite right. If you’re stimulating muscle growth by lifting weights, you’ll burn around 300 calories for every hour you spend lifting. Then you need to eat the extra food, which takes energy to digest. Once you’ve digested that food, some of the energy is used to fuel muscle-protein synthesis (study, study, study). In the end, it can take anywhere from 1,500 to 2,500 calories to build a pound of muscle.
Once you’ve built that pound of muscle, you also need to maintain it and carry it around. This burns another 12 or so calories per day. That isn’t much yet, but as you get deeper into a bulk, the extra muscle adds up. By the time you’ve gained 20 pounds, that’s another 240 calories you’re burning every day. To keep building muscle, you’ll need to factor that in.
Hardgainers & the Role of Genetics
Different people have different metabolic rates. Much of this is explained by how much you weigh and how much you move, but genetics also plays into it (study, study, study, study). There are outliers on either side. That’s why some people can build a pound of muscle with as few as 1,500 calories, whereas others need closer to 2,500 calories.
I wrote a full article about hardgainers on Bony to Beastly. I’m in the middle of writing another article about variations in metabolism. I’ll link that here when it’s ready.
How Many Extra Calories Should You Eat?
Now we get to the important part: how many extra calories should you eat to maximize your rate of muscle growth? There are a few different paths you could take:
- If you want body recomposition, building muscle while losing fat, you don’t need a calorie surplus. You can build muscle by getting energy from the fat you burn. This works best for overweight and “skinny-fat” people.
- If you want to do a classic bulk, building muscle quickly and leanly, start with a calorie surplus of around 400–500 calories per day. That will have you gaining around 0.5–1 pound per week. This works well for the average person trying to build muscle (study).
- If you want to do a lean bulk, keeping your gains as lean as possible, start with a calorie surplus of around 200–300 extra calories per day. That will have you gaining around 0.25–0.5 pounds per week. This works best for people who gain fat easily.
- If you want to do an aggressive bulk, maximizing your rate of muscle growth, start with a calorie surplus of around 500–1,000 calories per day. This works best for skinny beginners.
If you’re curious about how many calories you’ll need to eat overall, here’s a calorie calculator. There’s a dropdown menu that will let you choose your path. You don’t need to track your calories, though. All you need to do is add extra calories to your diet. You do that by having more snacks or eating larger servings.
The real trick is to weigh yourself every week, see how much weight you’ve gained, and then adjust your calorie intake accordingly. If you want to gain weight faster, add another 200 calories. If you want to slow things down, eat 100 fewer calories. Keep weighing yourself and adjusting.
Alright, that’s it for now. If you want more muscle-building information, we have a free muscle-building newsletter. If you want a full exercise, diet, and lifestyle program to help you build muscle and improve your health, check out our Bony to Beastly Program (for guys) or Bony to Bombshell Program (for women). Or, if you’re already an intermediate lifter, check out our Outlift Hypertrophy Program.