The daily exercise of recording what you consume, when you consume it, and any physical reactions, thoughts, feelings, etc that come up can help you to identify reactions and habits that you may be unaware of. Such as foods and beverages that your body may be having negative reactions to as well as habits that may be on autopilot that is un serving to your health. It can also help identify emotional consumption habits.
Journal also includes a daily prompt to guide you towards eating a clean diet free from animal products, processed foods, gluten, sugar, soy, alcohol, and caffeine over the course of 28 days if you so desire. The first 14 days are used to gradually wean you off of the above with the last 14 days used to eat a clean, vegan, gluten-free, sugar-free diet. You don't need to do anything other than follow along with the daily actions and remove items slowly from your diet as prompted.