For the first couple of days, I could eat at the inn just after dark, or when I woke up in the morning. Since then, I just get a "You're no longer hungry, and you're no glutton - at least not for the food here!" message when trying to sit down. My rations still decrease normally, so apparently I'm eating before I should be eating in order to get a free meal.
This is as a sorcerer, started on Day 3 in Act 1, and is still happening in Act 2.