What about finding vegan recipes he can try? I think the snacks are a good idea to try.

Poor thing. I'm sure its frustrating seeing someone, especially a loved one, do that to themselves.

Wait, no carbs? Does he not understand his body cannot survive without carbs?? The natural ones found in rice, beans, veggies, fruits are necessary for survival.

Upon second thought, maybe a book on vegan diet, the healthy way.