I always do my cardio at 24 hours fasted. This means I’m running on body fat reserves at that point. Compared to exercising unfasted I find my total output is lower. I can’t do as much intensity. But I also find that the energy is still reasonably high and is more even throughout the session. I always go 45 minutes and my energy level feels constant. I actually prefer it.
I do cardio/lifting in the mornings while I’m still fasting. I prefer it, I feel I have more energy than if I had eaten before. I don’t feel so heavy. I do cheat and have milk in my coffee but besides that still fasting. My cardio isn’t hardcore, usually a one mile jog or some elliptical.
Lifting/light cardio (running, sprinting, rowing) is fine for me.
HIIT will make me vomit water and stomach acid every time. I think mainly my recovery window gets longer, and trying to push through that with intervals is what rocks me.
Ive had this problem ever since I was a kid trying to work out hard after skipping breakfast though
I lift MWF and cardio TTh. I like it because I usually feel fatter in the morning from dinner the night before so it’s nice to get a jump on those calories before the pangs start later in the day. Also, I just don’t have time as my eating window is also the busiest part of my day.
My only challenge is that I get really hungry after a workout so it’s hard to wait those 3-4 hours after without a protein shake or something small. On heavy days I’ll just adjust my fasting time and stop eating earlier in the day so I can eat after the workout.
I have been doing heavy training because of a work injury. Trainings last 5hours mostly weight lifting 3times a week and I fast the whole time.. the first weeks were hard and usually at the end I’m pretty exhausted but most people don’t weight train for 5 hours.