You have not to search for Fastfood in Alanya. On every corner you will find thoose mostly little food shops. Big players like McD, BurgerKing you also will find several times in Alanya.

It´s an good idea to follow local turkish people and choose what thoose are eating.  You will find many little kitchens which provide fresh food like  chicken curry with rice and some nice mixed salad for some cheap money.

Additional to Fastfood you will many many Streetfood Shops which offers  you the typical turkish Köfte and Kumpir.