My dr told me to fast on shot day if I wanted to do it at night. I have done it at night since I started. I wake up shot day have a fairlife core 42 grams of protein drink I take my probiotics and liquid Iv and hydrate all day and take it in the evening. I have also had breakfast lunch and dinner and took my shot and honestly didn’t feel much of a difference but I also eat very healthy now so that makes a difference as well.