To Fast or Not to Fast? Many tests do not require fasting, but lipid panels (also known as cholesterol tests), glucose testing, and stool tests are a few that do. If your provider orders blood work during a visit, be sure to ask your provider if you need to fast beforehand. Fasting means that, with the exception of water, you refrain from eating or drinking for a minimum of 8 hours (10 to 12 hours is preferable) prior to the draw. This means no coffee or tea, so save that morning trip to the café for after your draw. Taking your vitamins or medications is OK, though.