1. It's not rocket science, it's just water retention. I used to enjoy a nightly snack of Cheezits. You know the little buttery cheesy crackers. I went for two years eating them nearly every night (around midnight) and then wondering why in the heck I could not get rid of the pudge.
Duh! Now that I've gone (mostly) gluten free and given them up (yes, I do miss them), I don't wake with pudge that won't budge. It's not a perfect plan, but it has worked for me. What do I eat instead? Well, I try not to eat at all late at night, but when I must have something, a few rice crackers or small bowl of plain, lightly salted popcorn works.
2. Drink a smoothie a day. Not a junk-food smoothie from a place where frozen yogurt is included in most of the offerings, but a real yogurt, green powder, protein powder smoothie. Here again, I've given up whey protein or veg protein. They whey made me bloat. If you drink one a day with real yogurt (try to keep the sugar to a minimum), add a little frozen fruit, some protein and fiber powder, it's a great meal replacement and really helps keep the "system moving" if you get my drift.
3. Water: Yes, drink plenty but don't overload yourself. I have found a drink several glasses a day plus a couple of cups of coffee and a cup of tea in the evening (decaf green). I don't obsess; I just stay hydrated and make sure to keep my water glass filled and near me.