Garrett was on Royal Canin when I got him, and boy did he love eating poop
I did the whole pineapple thing, but I wouldn't say it worked, I still had to watch him like a hawk [we were doing pee pads at this time].
As suggested by YTers, I decided to switch to Canidae, we switched food cold turkey, he had no stomach problems and wouldn't you know - HE STOPPED EATING HIS POO
! Just like that.
When we started going potty outside, the first time he pooped, he turned to smell it and my heart jumped, I though "oh no, he's gonna eat it". Well he sniffed, sneezed and walked away...
Hasn't touched it since....hopefully he wont regress.
I since changed him to FROMM Kibble and various canned, and he's been good. They actually poop less when they eat a high quality food - from my own experience and my friends who I switched to top brands.