Is Intermittent Fasting Really Worth It?

After all, 16 hours is a long time to go without eating. Here’s everything you need to know about the popular weight-loss routine – including whether it actually works

- Alex Shultz

Chris Pratt! Hugh Jackman! Halle Berry! Kourtney Kardashian! What these celebrities have in common, other than a gratuitous exclamation point after their names, is a professed fondness for intermittent fasting, the diet craze turning the fitness world on its sweaty, well-toned head. For help determining whether you, too, should incorporate this into your plans, we asked a few experts to explain what it is, why people love it, and whether it’s really worth the pain of forgoing on-demand snacks for the whole winter.

What exactly is intermittent fasting?

Intermittent fasting, unlike many other diets, is famously flexible in that you choose the days and hours during which you think it’s best to fast. The two most common methods are the 16:8 strategy – where you eat whatever you want (within reason) for eight hours a day and then fast for the other 16 – and the 5:2 method, where you eat normally five days a week and then keep your food intake to roughly 2 092-2 510 kilojoules for the other two days. It’s kind of a simplified-kilojoules math problem that’s supposed to prevent the yo-yo effect of weight loss and weight gain.

‘There are different ways to do this diet, but the bottom line is that no matter which you choose, you’re taking in less energy, and because of that, you’re going to start using your own body stores for energy,’ says Lisa Sasson, a clinical professor of nutrition. ‘If you don’t, you’re not going to lose weight.