When we're trying to lose weight, we usually think about what we can and can't eat. Bye-bye beer and burgers. Helloooo carrots and kale! But with intermittent fasting, the focus is on when you can and can't eat. 20:4 intermittent fasting comes in hot with a 20-hour — yes, a 20-HOUR — fast and a 4-hour eating window. It sounds a little extreme, huh? So … does it work? Is it necessary to fast that long in order to lose weight or improve your health? Is it even healthy to go 20 hours a day without eating? Let's get some answers.