"Hydration: I've noticed that I'm not so thirsty anymore, eating meals with so much vegetable matter, possibly because there's a lot of water in amongst the fiber and it gets freed up during digestion? "
That's one reason. The other reason is, that the more sugar you eat, the more water you need.
I'm getting better at not eating "just because" or based on what time of day it is or that I won't be able to eat for a few hours (trying out fasting a few times helped me be okay with going without- I'm not going to die that easily. Probably has roots in a stressful childhood where eating was an escape from family strife). Sugary foods are so easy to eat and a difficult treadmill to dismount. So far it's like a local maximum that's still too easy to roll off of but it feels so good up there when it all comes together.
Fasting is the most easy for me, when I am busy (preferable in nature on a hike). But when I am at home, surrounded by all kinds of food and kind of bored - then yeah, it can be hard.
That's one reason. The other reason is, that the more sugar you eat, the more water you need.