I do 16:8 or 18:6 fasts M-F with the occasional 24 hour fast thrown in on Mondays. I want to do a 72 hour fast for the benefits such as autophagy and insulin sensitivity. However I work out a lot, I lift 4 days a week and bike 4 days a week and they alternate. My bike rides on the weekend are 2-3 hours so I don’t feel like I can fast on the weekends. If I were to do a 72 hour fast should I just plan to not do cardio? I don’t want to end up passing out. Anyone else have experience with this?
Do not do cardio. Or at the very least do not do any intensive cardio. At most do a light, steady walk for a bit but biking/jogging is a very bad idea. I tried to do a quick two mile jog during a 48 hour fast towards the end of it and was lightheaded and stumbling by the half mile mark and felt terrible. Was able to slowly walk the rest of it but from personal experience, do not recommend anything more intensive than that.
I will offer a contrary experience. When I was cutting weight last year I regularly did 88hr fasts. I had no problem exercising cardio or weight lifting while fasting. My cardio workout is 30min intense, weight lifting 45 sets in 90min. I also went on brisk walks maybe 1hr. It just never felt different than normal to me orher rhan empty stomach hunger so I drank water frequently. I think one needs to get to know your response to fasting and judge what works but don’t assume that you can’t do anything. I would also (and did) consult with my doctor they should know your individually medical circumstances.