1.6 Grams of Protein a Day Per Kilogram of Weight

To answer the simplest question of whether taking in more protein during weight training led to larger increases in muscle size and strength, the researchers added all of the results together. [...] But those who did ramp up their protein gained an extra 10 percent or so in strength and about 25 percent in muscle mass compared to the control groups. The researchers also looked for the sweet spot for protein intake, which turned out to be about 1.6 grams of protein per kilogram of body weig...