More protein being good for fitness is a myth. Protein is the food for growth and repair. If you have too much protein, you are not building your muscles but actually breaking them down. Protein breaks down into amino acids which are acidic and need to be neutralised, which is in turn done by leaching the calcium from the bones to break down the muscles to produce ammonia.
Lack of protein is almost impossible on a whole food plant-based diet, as the largest sources of protein are beans and greens. Your body knows what it wants and will let you know through cravings and hunger. Always follow these indications as long as they are foods meant for the human species – fruits, vegetables, nuts and seeds.