I don't know why it wouldn't be... Unless it tricks your body into producing insulin, but it's so bland I doubt it would.

Well, the verdict isn't really out yet, but supposedly it's bad for you, even plain. Here's why (as far as i've read):

1. The carbonation irritates the stomach.
2. The stomach "cures" the irritation the only way it knows how. It adds the only antacid at its disposal: calcium. It gets this from the blood.
3. The blood, now low on calcium, replenishes its supply from the bones. If it did not do this, muscular and brain function would be severely impaired.

Over time you get sucky bones.

Thanks I was just wondering. I'll stick to regular water.