That my friend is broscience. Sure the fasting phase will be more catabolic then if you were eating during that time BUT what most people forget about is that fat loss is a catabolic process aswell .... Wanna stay anabolic 24/7 ? Forget about getting lean ...
And after the catabolic (fasting) phase comes the super anabolic (feeding) phase. You workout fasted which dramatically improves insulin sensitivity and you deplete quite a lot of your glycogen ... Then you have the biggest meal of the day post workout. This is the super window of anabolism and your body will use most of the nutrients consumed at that time to replenish muscle glycogen and for muscle growth. In such conditions there is no way it could end up stored as fat (unless you would be grossly overeating that is)
Muscle growth is not about staying anabolic 24 hours a day, it's about "anabolic minus catabolic" . Stay in the anabolic area too long and you'll gain muscle but unfortunately also lots of fat. stay in the catabolic for too long and you'll lose (also, both muscle and fat) It's all about finding just the right balance
Do you follow IF both bulking and cutting? Just cutting? Also does IF equally well for someone natural vs on gear? Just curious. I'm considering doing IF for about 4 weeks while I take my SARMS which will be inbetween powerlifting meets for me. After the sarm run i'll be going all natural and bulking up/carb loading for my july meet