Intermittent fasters: When do you do your HI workouts?

I just jumped back into IF few days ago with an eating window between 3pm and 10pm.
I also intended a kcal defincit of around 400kcal daily, but so foar I am probably closer to 900.

In any case, I am still adapting. But I started to experiement with workout times.
So far I tried right in the morning (fasted), early afteroon (fasted) and 2h after breaking the fast with a light protein rich meal only.

So far I can’t say that I felt a huge difference, it all was utterly exhausting (as always).

I wonder what others might have experienced, combining HI training and IF for longer? What time worked best for you doing your HI workouts?

Depending on your FTP (if it is higher than 4.5 W/kg or something like that) I think it really only matters for longer sweetspot and threshold workouts provided you ate enough before and didn’t do HIT the day before

Unfortunately rather around 3.0.
But what you say is also what I thought. I guess it shouldn’t matter if I charged my glycogen stores after of before bed time.

I used to do more fasted rides, the problem is I feel so weak that I stooped. I couldn’t keep up with a easy endurance/recovery 90 min outside.

Last Sunday I was doing an endurance ride while listening podcast and the theme was fasted rides. I need to confess that I was riding outside, volume very low so I lost a good amount of details. I’ll listen to it again. But bottom line is: fasted rides aren’t as good as we think. In fact, they are prejudicial.

that is the link


The problem with all the science dismissing know keto/fasted riding for endurance is that the adaptation period in most research is way too short. It should be 4 month minimum


I fast 8pm to 11:30-12 depending on my schedule, I do my HIT at around 5:30-6:00PM and never seemed to have issues.


Yeah, leaving fasting as weight management tool aside, for training purposes I like doing intervals late in long Z2 rides instead (a la SS or Z4/4x5-10 with 5min recovery after 2-4h of Z2).

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I’m similar to this. 7.30pm to 10.30am fasted, mainly to give my gut a rest, rather than to reduce calories or train fasted for fat adaptation.

On the turbo around 4pm. I would notice a difference if my late breakfast and/or lunch is low in carbs.

I even din’t know I do intermittent fasting, I called it life :wink:

Given I am part of this - for me it’s all about carb based breakfast, without that no high intensity that day. If no breakfast at all, due…life, then even with big lunch endurance ride is max I’ve got in me without digging a hole in the next days.


I eat between 10am and 6pm. I do my high intensity training around 4pm and make sure I have plenty of carbs in the early meal. Then after my high intensity workout I have a nice dinner with protein and carbs. I would not advise doing high intensity training before your first meal while in a fasted state.

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I’m not the strictest intermittent faster at the minute - I was a bit more methodical a couple of years ago - but I more often than not don’t eat in the morning. I’ve done a fair bit of riding outdoor fasted - both short fairly intense and 4 hour+ endurance rides - and it’s generally worked quite well.

With family responsibilities some days can be time crunched, so I’ll occasionally do TR workouts early morning. This is fine for easier workouts, but 1 hour “hard” sweet spots and threshold I find too much and I’ve had a few DNFs as a result. I now try to move these to after work, or sometimes shift to the next day (shouldn’t really, but anyway…) which greatly improves my capacity to finish them. At any rate, I try to make sure I’ve eaten a few hours before


With a 16:8 IF approach I found the least bad time to do harder training was straight after work. E.g. Break the fast with lunch at around midday. Train at ~5pm when energy levels and glycogen stores are topped up from lunch and maybe a mid-afternoon snack. Refuel post-workout to ensure good recovery then don’t eat anything after 8pm.

But honestly I also found using IF to lose weight to be incompatible with making performance gains. I guess if coming from a low training base then fitness gains would still be possible. But if you’re already fairly well trained then making further improvements in my experience requires fueling pre, during and post workout which I found was compromised by IF. Could do both for a bit but at some point the wheels started to come off and I was lacking energy or motivation for those hard training sessions.

As a result I tend to use IF to lose or maintain weight in periods when for whatever reason I can’t train much or train hard. E.g. If I’m travelling with work a lot, it’s hard to maintain a regular training schedule, and there’s a lot of food temptation around, then IF is great for not piling on weight. But if I’m following a structured and progressive training plan then I find it better to lose weight (if needed) without resorting to IF.


I’v been doing IF for years on and off, usually with 16:8 type schedule. When I’m really adhering to it my eating was usually around 10 AM to 6 PM.

I think that wether you are an early riser, early sleeper matters. I happen to wake up early and be in bed pretty early too. In this way I have been able to do double day workouts quite easily with either my cycling or strength workout starting around 6 to 7 AM, then a busy morning before eating around 9:30 - 10 AM. This meal is balanced with plenty of carbs at least 25/30 grams protein and whatever fats.

Second session can be when early afternoon and if it’s a bike session I may have some light carbs before or during. I never had an issue with energy during my workouts doing it like this. Usually my biggest obstacle was eating enough by 6 which is kinda early with a family. I will say after a few weeks and being steady with it I would allow myself to eat either a little earlier or later if it was less stressful. This is especially true later into a build phase if my energy demands are higher or if I’ve been in a steady deficit and needed some more leeway in my plan to keep it sustainable.

I’d caution you of being in a severe deficit this early on of you are trying to drop some excess body weight. A day or two with 900 cal deficits once maybe twice a week is not that bad, but more than that may do more harm than good in the long run.

Good luck with it!


I use a typical 16/8 pattern with a window from 11-6. My training schedule is polarized (around days off and work schedule) with at least 1 interval session per week and one long (5+ hr) base ride.

Mon/Tues/Thurs/Fri/Sun; 30-60 minute, zone 1 power, basically a fasted recovery ride first thing in the AM, water/electrolytes but no calories. eat about 2 hours after finishing
Wed/Sat: start ride fasted but immediately start consuming carbs in drinks/gels, long (60 minute) warm up then intervals or long zone 2 ride.