If young guys who don’t work out much eat a plant-based or meat-based diet with the same amount of protein and lift weights for 12 weeks, they’ll gain about the same amount of leg muscle and strength.

If young guys who don't usually lift weights eat about 1.6 grams of protein per kilo of body weight every day—whether from plant-based foods and soy protein or from regular mixed diets with whey—they can get noticeably stronger in their legs after 12 weeks of weight training.

Young men who lift weights for muscle growth and eat more than 2.0 grams of protein per kilogram of body weight each day tend to get stronger on average than those who eat less than that amount, based on improvements in their squat, bench press, and deadlift numbers over 8 weeks.

If you lift weights and eat lots of protein, you’ll likely build more muscle and get stronger than if you just do one or the other—because together, they work better than alone.

For young men who exercise regularly, eating more than 2.0 grams of protein per kilogram of body weight per day does not lead to significantly more muscle gain than eating less than that amount over an 8-week resistance training program.

If guys who already lift weights drink a 20g protein shake after working out for 9 weeks, they’ll gain more muscle and get stronger—even if the protein is a mix of fast- and slow-digesting types.