Weight gain is a problem for most of us, especially during the holidays. Some may not be happy with that newly found weight and will be ready for some fasting! What if you could follow an eating plan (not a diet!) that helps you lose weight and burn body fat, improve your overall health—including cardiovascular, metabolic, insulin and blood sugar, brain function and anti-aging—while allowing you to eat your favorite foods most of the time? Intermittent fasting does all of that, which is why it is now the fastest-growing eating lifestyle.

Fasting itself has a history that goes back millennia: the ancient Greeks used it for health and mental clarity, and all the major religions include some form of spiritual fasting. Today’s fasting offers two new twists: reams of science and clinical studies showing why and how it works, and various plans that incorporate intermittent periods of fasting, making it much more sustainable (and even enjoyable).This updated guide begins with a deep dive into how intermittent fasting works in your body, producing just enough occasional cellular stress to make you stronger, while lowering insulin to “unlock” your fat stores so you can burn them off. Then we present the nuts and bolts of following four different kinds of fasting, from time-restricted (eating within an 8-hour window) to alternate-day to the Warrior plan (one meal a day). Readers will learn strategies for how to start and break their fasts, how to choose the best form for them, what to do about hunger (it’s not as hard as you think!), getting past stuck points, using the right supplements, and dealing with side effects. Finally, we offer inspiration: stories of both “regular folks” and celebrities who swear by fasting, and an exploration of the way it can change your relationship with food and eating.