Calorie surplus for muscle growth: how much is enough?

Do you even need a surplus to build muscle?

If you want to build muscle in a targeted way, yes. A surplus isn't strictly required for muscle to grow at all, but it makes the process much easier to plan. Your body then has enough energy for training, recovery and building new tissue. Beginners and people with a higher body fat percentage can also build muscle without a surplus. That is called body recomposition.

How big the surplus needs to be is still an open question in the research. One review concludes that an energy surplus supports muscle growth, but that the ideal amount for people who lift has never been properly tested (Slater et al., 2019). The guideline values below are therefore a sensible starting point that you fine-tune based on how you actually progress.

How big should your calorie surplus be?

About 10 percent above your total expenditure. With a total expenditure of 2,000 to 3,000 kcal, that is 200 to 300 kcal a day. A review on nutrition during a building phase gives 10 to 20 percent as the range and explicitly recommends a smaller surplus for experienced lifters (Iraki et al., 2019). I deliberately start at the low end, because it is easier to add a little more later than to lose fat you didn't need to gain.

Here is a fully worked example, calculated exactly the way the calorie calculator does it with the goal set to muscle gain: a man, 28 years old, 180 cm, 75 kg (165 lb), lightly active day to day, strength training four times a week.

The surplus here is 251 kcal a day. On paper, that means his weight goes up by about 0.23 kg a week, or 0.3 percent of his body weight. That sits right in the middle of the sensible range.

Why more calories don't mean more muscle

Muscle growth has a speed limit, set by your training, your experience and your recovery. Calories beyond that mostly end up as fat. A study of 39 elite athletes who were asked to gain weight over eight to twelve weeks shows this. The group following a nutrition plan ate on average about 600 kcal more per day than the group that ate by feel. Their body weight went up by 3.9 percent instead of 1.5 percent, and their fat mass by 15 percent instead of 3 percent. The gain in lean mass, however, was no different between the groups (Garthe et al., 2013).

So a surplus that is too big costs you time later on: every kilo of fat you pick up unnecessarily while building has to come off again in a diet.

How fast should you gain weight?

By 0.25 to 0.5 percent of your body weight per week. Beginners can use the whole range, because their bodies respond to training more quickly. More experienced lifters tend to stay at the lower end, since they build muscle more slowly anyway (Iraki et al., 2019).

Keep in mind that these are averages over several weeks. Individual days often fluctuate more than the whole week's gain because of water, salt and carbohydrates. So weigh yourself at the same time each day, take a weekly average and only compare weeks with each other.

How to split protein, fat and carbohydrates

Protein comes first, then fat, and the rest is carbohydrates. For protein, it's 2.0 g per kilo of body weight, the same as in every phase. In a large meta-analysis, going above roughly 1.6 g brought no additional gains, with the statistical uncertainty extending up to 2.2 g (Morton et al., 2018). 2.0 g sits within that range. How to spread that amount sensibly across the day is covered in the article on protein requirements.

Set fat at 0.9 g per kilo (range 0.8 to 1.0 g) and don't push it unnecessarily low. The remaining calories come from carbohydrates. During a building phase they are the fuel for your training, and they belong mainly in the meals around your sessions.

When and how to adjust your surplus

Wait for a clear trend over at least two weeks before you change anything. At that point there are three typical situations:

• Your weight isn't moving: No meaningful gain over about two weeks. Add 150 to 200 kcal a day, no more.
• Your weight is going up too fast: Clearly above the planned range, and your waist is growing with it. Check your surplus and reduce it.
• Your weight goes up, your performance doesn't: More calories won't help here. Look at your training and recovery first.

Only ever change one thing at a time, so you know what made the difference. Whether your training is really moving forward shows in the weight and reps on your main lifts. When to increase the weight there is explained in the article on progression in strength training.

When the building phase ends

A building phase has a fixed time frame. Eight to twelve weeks is a realistic interval for taking stock: weight, waist measurement, photos and strength numbers together. If your weight is rising in a controlled way, your waist isn't growing out of proportion and your strength numbers are improving, you can keep going. If your body fat has clearly gone up or you no longer feel comfortable, follow it with a maintenance phase or a short diet before the next building phase begins.