Expert Tips For Intermittent Fasting To optimize your time on intermittent fasting, here are some expert-approved tips: Fast for at least 12 hours a day (although 13 is ideal). If you're looking to lose weight, you should still eat in a healthy calorie deficit during your feeding window, especially if you're doing Leangains (to calculate your calorie target, use this formula). If you're doing 5:2, you can eat more calories on your feasting days; you don't need to eat in a calorie deficit on those days since the two fasting days will give you an overall weekly deficit. If you need some help, check out these five apps. Curious what you should eat during your feeding window? Here's what the experts recommend and what one day of eating on intermittent fasting looks like. Image Source: Getty / Plume Creative