I do HIIT 3x per week (30 min sessions) and would like to start doing this in a fasted state. However, my training is at 4:30 pm. What would the ideal schedule look like in terms of eating / IF ? I have no problems fasting all day and consuming my first meal after my 4:30pm workout; however, is this too long of a fast? Would I be better off eating breakfast and then nothing else until after working out? All advice is welcome!
When I first started IF (Lean Gains) I asked the same question, since a 1-9 feeding window was ideal. I was always scared to push working out beyond a 16-hour fast when I couldn't work out in the morning - thus doing HIIT (kettlebells, sprinting) on a 20-ish hour fast around 5:00. That said, I did it anyway simply to experiment. The first few times were rough (foggy, lack of energy) but after a week or two of adjustment, it feels no different from my typical schedule.
You've probably already seen graphs similar to the one here: http://rippedbody.jp/when-not-to-do-cardio/
I recall better ones that illustrate fat-burning beyond the 16 hour range, but essentially, regarding ketones, etc. 16 hours is not much different than 21-22 hours. Berkham, Sisson, Pilon etc. don't advocate for much longer than 24.
But, it does present one option of pushing your window the previous night to say 10:00pm and breaking your fast later the next day. Three times a week? Do-able. And dinner that night will be awesome.
I work out in the fasted state, though it's always in the morning. I have no trouble fasting well into the afternoon, but I've never tried an intense workout at that point in a fast. For me, I think it would be rough. After fasting from 8PM to 2PM the following day, I am usually thinking about food and not kettlebell swings. Perhaps experimenting is in order. You could always try it a couple of times and see how you fare during your training. You could also try having breakfast in the morning and then fasting until after your 4:30 HIT session. I frequently play with IF and training times so I'll be curious to see answers from others.
I have been doing crossfit 3x per week at about 5:30-6:30pm, and usually have lunch at 12:00pm and nothing else before the workout. The first few times it was kind of rough and I ran out of energy, but after a couple of weeks it is now ok. I think doing the workout fasted helps with fat burning and "girth loss".
I have not tried skipping lunch or fasting all day before the workout, and think that might be overdoing it, since the workouts are pretty intense. Maybe depends on what you are trying to achieve, but longer term, I think you need to make sure your muscles have the energy they need,
I do make a point of eating some carbs after the workouts which usually means sweet potatoes. For me, trying to remain very low carb every day while doing hard workouts causes me serious energy and metabolism problems after a couple of weeks.
Experiment. I can do exactly what you are saying no problem. I do it about once every 7-10 days. If you try and don't feel you have the energy, then try with breakfast. It will probably be a good learning experience. I think if you are quite fat-adapted, you won't have much of a problem waiting until after your workout to eat. JMHO