I am no nutritionist, but I think that a football player, like most athletes, should have a balanced and healthy diet! Avoid eating lots of fried food, like chips and fried chicken, or fatty food like burgers and bacon. Grilled or baked chicken and fish, eggs and pulses are very good sources of protein! Also, fruit and veggies are very good sources of vitamins that are important for a strong body!
As Zena mentioned, it is thought that athletes should eat healthily – but eat lots of energy rich foods, in the form of protein rich foods, but avoid fast foods. Did you know beans and other pulses are very good protein sources if you are a vegetarian or cannot eat meat or fish?