I recently completed a 72-hour fast this past weekend. I broke my fast with a bulletproof coffee, then had some bone broth about 45 minutes later. About an hour later, I ate salmon, bacon, and eggs. I didn’t experience any digestive issues. On the second day, I ate two full meals like usual.
I participated in my karate class, where the workouts are usually pretty intense, and I didn’t have any issues.
You could try your workout and just monitor how you’re feeling.