It seems like the prevalent theory is more protein = more mass. Common relations seem to say at least 1g protein per # of body weight (bw) to 1.5g per # of bw. I've seen people suggesting 2g per # per bw for big growth.

What is the point of dimishing returns on this curve? If it's 1g. No, 1.5g. No, 2g. Why not 2.5g? Or 3g? Why not 10? I'd be huge! Where does the curve start to dip significantly?