A lot of us reach for a hot cup of coffee every morning to start the workday. It keeps us alert and productive, right? At it’s core black coffee does, but all the extra syrups, artificial flavorings, and preservatives can leave us feeling pretty crummy. A lot of the foods we eat dictate how sleepy or how awake we feel. Specific foods and preparations—including sugar, refined carbohydrates, unhealthy fats, and salt—can negatively affect brain function and thinking processes. A quick trip for a convenient fried lunch can weigh on the digestive system for hours. Read on to learn which foods and drinks you should steer clear of at work in order to feel better and avoid sleeping at the keyboard.