Wikipedia defines Intermittent fasting, also known as intermittent energy restriction, as an umbrella term for various meal timing schedules that cycle between voluntary fasting and non-fasting over a given period. Three methods of intermittent fasting are alternate-day fasting, periodic fasting, and daily time-restricted feeding. Alternate-day fasting is the method where you eat on certain days and consume no food on other days. Sample schedule would be Sunday Eat Monday NO Food Tuesday Eat Wednesday No Food and so on! Periodic fasting is pretty much the same as alternate-day fasting expect with this method you don't have to be as strict with the days that you are going to fast. The most popular and where I believe all beginners should at least start is the daily time-restricted feeding. You can fast anywhere from 12-36 hour at one time. When making any change to your diet especially if you have health concerns you should always seek the advice of a medical professional.