I usually eat like four slices of ciabatta a day.

That isn't in your food log. The fact that you really like a food doesn't mean you can rule it out as a poison.

I realized that I would also be quite put out if I had to restrict my sugar intake.

You'd go into withdrawal, but the withdrawal symptoms and cravings would go away within two weeks. The body uses sugar first for energy, then fat; if you're eating lots of sugar, it needs to transition to metabolizing fat (ketosis), and it's short on energy in the interim, which is a little unpleasant. But it's better on the other side.