When you have Invisalign clear aligners on, you cannot eat or drink anything except water. They are typically worn for 20 to 22 hours a day. The aligners must be removed for eating, since food and drink can get stuck in them. As a result, plaque can accumulate on your teeth and gumline, causing cavities. You may also stain your teeth and your aligners if liquid seeps into them. But there are no restrictions on what you can eat or drink when you remove your clear aligners.