Among them, fasting is simple, free, convenient, effective, and allows you to enjoy life’s occasional indulgences. You can do IF on almost any plan, whether you’re vegan or paleo, and it gives your overworked digestive system a much-needed break. At the same time, no one plan works for everyone, and that includes IF. Even Fung notes certain people shouldn’t do IF, including pregnant or breastfeeding women, underage people, and malnourished folks. He advises others like people with type 1 diabetes to proceed cautiously with fasting. While you can usually work with a credentialed health care expert and modify fasting to your condition, I’ve found people with these five issues should think twice about, and—in one case—absolutely avoid intermittent fasting: If you don’t fall into those conditions and want to try IF, start out slowly. Have a big dinner, close up the kitchen for the night, and then have breakfast as late as possible the following morning. That creates about a 12-hour or longer fasting window—most of it while you’re sleeping—that helps your body dip into those fat stores. Gradually increase that fasting time, but if you feel nauseous or otherwise unwell, please eat something. Don’t risk your health!
