Generally speaking, your teeth should only remain sensitive 48 to 72 hours after the whitening process is complete. From this point onward, you can basically eat anything you want. But until that time, you might want to avoid things like ice cream, tea, coffee, sweets, anything acidic, and excessively hot meals. During your whitening process, you might want to avoid these foods altogether. You might also consider drinking out of a straw, as this helps protect your sensitive teeth.