The only thing that will tone up your arm musclesis exercise. Yes foods do help by providing energy for you to exercise. Also eating fruits vegtables and all those healthy things wont cause you to gain bad fats. Hope I helped :)
Get off junk food & eat more lean meats, all types of vegs cooked & uncooked, plenty protein enriched foods & calcium (milk) for better protein absorption and good resistance workout plan. Seek help for supplements at GNC store.