Calculating Macros for Muscle Gain

Gaining muscle mass is not 'eating everything in sight' but a controlled energy surplus with the correct distribution of macronutrients. The editorial team explains step by step how to calculate calorie intake and macros for gaining mass, which figures are backed by research and where people most often make mistakes.

Step 1: baseline calorie intake

Any calculation begins with an estimate of daily energy expenditure. First, the basal metabolic rate is determined — the energy the body expends at rest. Most often the Mifflin–St Jeor equation (1990) is used for this, which in studies has shown better accuracy for the modern population than the older Harris–Benedict formula.

For men the formula is: 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5. For women the last term is replaced by −161. The resulting value is multiplied by an activity coefficient: approximately 1.4–1.5 for people with sedentary work and 3–4 workouts a week, 1.6–1.8 for physically active professions or daily training.

It is worth remembering that any formula is only an approximation. The error for a specific person can be several hundred kilocalories, especially for people with large muscle mass or an unusual lifestyle. So the calculation is a starting point, not the final answer.

A more accurate, though slower, method is to keep a food record for two or three weeks at a stable weight. The average actual calorie intake over this period will be your real maintenance level, from which the surplus is then added.

Step 2: the size of the surplus

Intuition suggests that the more you eat, the more muscle will grow. In reality the rate of muscle protein synthesis is limited, and an energy surplus beyond a certain threshold goes predominantly into fat tissue. The review by Slater and colleagues (2019) concluded that the optimal surplus size for hypertrophy has not been precisely established, but an excessive surplus increases primarily fat mass.

A review of recommendations for bodybuilders in the off-season (Iraki and colleagues, 2019) suggests aiming for a moderate surplus that provides a gain of about 0.25–0.5% of body weight per week. Beginners can grow faster; experienced athletes should aim for the lower end of the range.

In practice this usually corresponds to a surplus of about 10–20% of maintenance calories. For a person with a norm of 2600 kcal that is about 250–500 kcal a day above the norm. This approach allows mass to be gained without the need to then 'cut' for a long time afterward.

The surplus is controlled not with a calculator but with the scales: weighing in the morning on an empty stomach several times a week and comparing average values across weeks. If the weight doesn't move for two weeks, add 100–200 kcal; if it is rising much faster than the plan, reduce it.

Step 3: protein, fats, carbohydrates

Protein is the most important macronutrient for hypertrophy. The meta-analysis by Morton and colleagues (2018) showed that the gain in lean mass in combination with strength training stops increasing noticeably at about 1.6 g of protein per kilogram of body weight per day, while the upper bound of the confidence interval reached about 2.2 g/kg. The ISSN position (Jäger and colleagues, 2017) recommends 1.4–2.0 g/kg for most active people.

Fats ensure the synthesis of steroid hormones, the absorption of fat-soluble vitamins and the palatability of the diet. For gaining mass, 20–35% of total calories or roughly 0.8–1.0 g/kg is usually recommended, with an emphasis on unsaturated fats and a sufficient amount of omega-3.

Carbohydrates fill the rest of the calories. They replenish glycogen stores, which allows training with high volume. The ACSM position (Thomas and colleagues, 2016) for moderate and high loads gives a range of about 5–7 g/kg per day, although for strength disciplines lower values can also be sufficient.

The distribution of protein throughout the day also matters: 3–5 meals of 0.3–0.4 g/kg provide better stimulation of muscle protein synthesis than one or two large meals. This aligns with the ISSN recommendations.

Example calculation and adjustment

Let's consider a hypothetical man aged 25, 75 kg, 180 cm tall, with 4 strength workouts a week. Basal metabolic rate: 10 × 75 + 6.25 × 180 − 5 × 25 + 5 = 1755 kcal. With a coefficient of 1.55, maintenance is about 2720 kcal. We add a surplus of ~300 kcal — a target of about 3000 kcal.

• Protein: 2.0 g × 75 = 150 g → 600 kcal;
• Fats: 1.0 g × 75 = 75 g → 675 kcal;
• Carbohydrates: (3000 − 600 − 675) / 4 ≈ 430 g → ~1725 kcal (≈5.7 g/kg).

Then comes the most important part — monitoring. After 2–3 weeks the average weight is compared with the target rate. If the gain has slowed, calorie intake is increased mainly through carbohydrates; protein is usually kept stable.

Common mistakes: an overestimated activity coefficient, a 'dirty' bulk with excessive fat, underestimating the calories of sauces and drinks, and abrupt changes to the plan because of daily weight fluctuations related to water and gut contents.

Editorial conclusions

Calculating macros for gaining mass consists of three steps: estimating maintenance calorie intake, a moderate surplus and the distribution of macronutrients with priority on protein.

The best-supported data concern protein: about 1.6–2.2 g/kg per day. For the surplus, a reasonable strategy is a small excess with control of the rate of weight gain.

Formulas give only a starting point; the real figures are refined by the dynamics of weight, strength performance and girth measurements.

We also recommend our articles on calculating macros for weight loss, on the distribution of protein throughout the day and on nutrition before and after training.

References

1. Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241–247.
2. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376–384.
3. Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20.
4. Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine joint position statement: nutrition and athletic performance. Med Sci Sports Exerc. 2016;48(3):543–568.
5. Iraki J, Fitschen P, Espinar S, Helms E. Nutrition recommendations for bodybuilders in the off-season: a narrative review. Sports (Basel). 2019;7(7):154.
6. Slater GJ, Dieter BP, Marsh DJ, et al. Is an energy surplus required to maximize skeletal muscle hypertrophy associated with resistance training? Front Nutr. 2019;6:131.