Those, and the lack of carbs.
If you were like me before I switched to zone, my body was getting used to the lack of carbs. Itll take a little time for your body to get used to the high amount of protein and fat thats in Zone. (this is all if you were eating like the average american, its okay, we all did)
You can try upping the fat to increase the calories a little. Zone seems to really limit calories, especially if youre higher in bf (>30). Drink your WHOLE milk, I think I saw you post about this in another post, PWO and eat your meal afterwards. I usually wait till I get hungry, an hour or two later.
Youll adapt. Just tough it out.