At the cost of repetition, here's why you need a food journal. You write down everything you eat, even that sip of a beverage your friend was drinking, even a bite of the deep-fried chicken steak your husband was enjoying. You write down the portions you have consumed, and the time at which you eat. Green Vibe Keto This allows you to review how exactly your diet is turning out, what you ate and shouldn't eat, and how you can change your diet plan to make it more effective. It will help you keep track of where you may be going wrong if the weight loss plan is not proving to be effective.