If i have my broiler chickens on a 24-28% protein ration, how will that effect my meat?

some people say its good because there less fat and they are getting the right amout of protein and will stay healthy, other say no- move them to 15% or so. whats the difference? i want the best ration that will result in non-fatty meat. we used to have ours on 24% and then 19% and we got real fatty meat. will feeding them higher protein get less or more fatty meat?