The Complete Guide To Fasting

by Jason Fung

In this forty-two-hour fasting regimen, you’ll fast for the entire day at least three days of the week and skip breakfast every day, regardless of whether or not you are fasting. On fasting days, you are only allowed fasting fluids (here). In the Intensive Dietary Management Program, we typically use this forty-two-hour fasting protocol for type 2 diabetes. The extended fasting period allows blood glucose and insulin more time to drop. However, if you are taking medications, you will need to consult your physician before fasting on this protocol, in order to avoid low blood sugar. While we want and expect blood sugars to drop, if you’re overmedicated, they may drop too low, at which point you may have no choice except to eat some sugar to raise it—which defeats the point of fasting. On eating days, we recommend you follow a diet that is low in refined carbohydrates and high in natural fats. Strive to eat only whole, unprocessed foods and avoid processed or prepared foods as much as possible. In the example below, you’d fast from dinner on Sunday night until lunch on Tuesday. If you finish dinner on Sunday at 7:30 p.m., then you would not resume eating until lunch on Tuesday afternoon at 1:30 p.m. On nonfasting days, you would consume lunch and dinner only, not breakfast.