Protein calculator for muscle growth

Where these numbers come from

In 2017, the International Society of Sports Nutrition (ISSN) published a position stand on protein and exercise. To build and maintain muscle mass, an intake of 1.4 to 2.0 g per kilogram of body weight per day is enough for most people who train.

A meta-analysis published the following year by Robert Morton and colleagues, pooling 49 studies and 1,863 participants, narrows that down: beyond about 1.6 g/kg per day, extra protein brought no further gains in lean mass. That is the value the calculator uses as its target.

When cutting

During a calorie deficit, the same ISSN position stand states that higher intakes, of 2.3 to 3.1 g/kg per day, may be needed to best preserve lean mass in trained lifters. The calculator then shows that range.

Spreading it across the day

The ISSN recommends servings of about 0.25 g/kg of high-quality protein, or 20 to 40 g, every 3 to 4 hours. For lifters trying to gain muscle, the review by Iraki and colleagues (2019) suggests 0.40 to 0.55 g/kg per meal, over 3 to 6 meals. Exact timing matters less than the daily total: the effect of training on muscle building lasts at least 24 hours.

To learn more, read our article protein for muscle growth: how much per day?

These guidelines apply to healthy adults. If you have kidney disease, are pregnant, take medication or have a medical condition, ask a doctor or a registered dietitian before changing your diet.

Sources

• Jäger R. et al., "International Society of Sports Nutrition Position Stand: protein and exercise", Journal of the International Society of Sports Nutrition, 2017.
• Morton R.W. 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", British Journal of Sports Medicine, 2018.
• Iraki J. et al., "Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review", Sports, 2019.