Physical fitness
When calculating the daily protein needs for marathon runners or competitive weight lifters, you should allow for approximately 1.2 to 1.4 grams of protein per kilogram of body weight. For marathon runners or competitive weight lifters the amount of protein requirement is definitely higher than those sportsmen who does less physical amount of work. For normal people that do not require great physical activity during their normal life, then those people will obviously require less amount of protein than the sportsmen in question. so we can see that amount of protein requirement varies with the amount of physical activity that is done by the person.
