That was one long sentence!
. But okay, feed him a healthy diet for dogs. I don't know what is available in your country and what your goals are: raw, cooked or kibble. What you are describing sounds more like what you would feed a rabbit.
Besides a good diet, give him good exercise, appropriate for his age and the shape he is currently in to avoid overdoing it.
Deja, GSD, sable WL, female, born 11 / 2013
Cam, Rough Collie, sable, male, born 8/2015