I'm a bodybuilder and I've been Intermittent Fasting now for about 3 years and have worked out 5 days a week most of that time. It's about all timing your meals properly. I work out in the evening so when I have a noon meal it gives my body enough time incorporate the food for fuel before the workout. My biggest meal is after the workout when my body is at it's anabolic peak. The funny thing thing is that you can still gain weight using this protocol and I've used it very well to pack on some additional muscle so it's not a free-for-all and you still need to eat clean 90% of the time.