Why does my dog go visious when go near his food?

i have a 7month old american bull dog! and when i put food in his bowl and place it on the floor! if you go any were near him! he gets visiouse and will go for you. or if he is leftin the kitchen and for example he get the bin bag, when we go into the kitchen he goes mental and again will go for you, the dog is very playfull and a good dog the only bad thing is his food any help please!!!! (people say gettin him neuted will help)