One thing I’ve found is that intermittent fasting works much better with a low carbohydrate or keto diet. I fast 16+ hours a day and lift weights in the morning after fasting 14 hours without any problem. If you keep your insulin in check (via not eating excessive carbs), your body can access its fat stores much more easily and burn those for fuel. I’ve been doing this for months, and I’m still making gains (maybe even better than before) from my workouts. I eat at least as much as before, and I’m also rarely hungry. I believe that the human body is designed to function on a low-carb diet and IF. You eat your food during that window, your body stores the excess as fat, and (if your insulin is in check from low-carb) your body uses that fuel for the rest of the day. I only wish I’d found all this out sooner.