Your db is split into front and back ends, yes? In that case all you lose is whatever you last saved as a copy.
If you're doing a lot of design changes because it's a work in progress then you should be backing up about every hour or so.
If your db is not split, then you have a larger issue, or one day will create a much larger issue when you lose all your data because of something like corruption.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.