The best way to define any type of fasting is to think of it as simply a change in eating patterns. In the case of IF, in place of three square meals in a day, or eating a handful of smaller meals throughout the day, there is a window of time when we're allowed to eat. Advanced Keto Reviews This could take the form of a few hours a day, or the fasting window could represent certain days of the week. During that time, we can eat whatever we want - within reason of course.