I’m starting intermittent fasting 16:8 and usually work out first thing in the morning with a session of 30-45 of cardio. That generally puts my next mail about five hours after that workout. Is that an issue or does not eating after a workout really only affect weight lifting workouts?
Best time for fasted cardio is as deep into the fast as possible.
You want your glycogen stores fully depleted and you want to be in ketosis. If you are there, you can do some pretty heavy duty cardio. Even after 24-48 hours of fasting. At least 1 hour even 2 hours of intense cardio have been no problem for me. Your body has all the energy it needs in your fat. But its key to be fully depleted and fat adapted so you can access all of it.
Take electrolytes and imagine you’re chasing A tasty animal through the woods.
Last time I did my keto+IF I did HIIT in the late afternoon and had awesome results. The benefit there is by late in the afternoon you are deep in ketosis. Now after about a year break from keto and fasting, I’m back on the diet and using IF. My schedule changed so I work out first thing in the morning. I don’t like it as much. You don’t produce as many ketones early in the morning and I have trouble being fully awake to get in a really killer workout. But getting any workout in is better than no workout, so I’d say do what works best for you and then optimize your lifestyle as needed as you move forward.