Intermittent Fasting and running (Read 85 times)


    Have not found much info on the topic of Intermittent Fasting (IF) and running. I Started IF 6 months ago and lost 16 lbs. easily (from 176 down to 160) and been maintaining that weight for 3 months now without any difficulties, fasting 18 hours per day with  a 6 hour eating window. I actually feel like I have more energy on a 10 mile training run after fasting for 16 hours than I used to before IF and still have energy left afterwards. Interested in getting thoughts from others here that understand IF and also are runners.

    TIA !!


      I do some sporadic IF. Once or twice a week for 14-16 hours. Since I do that at work it will sometimes go as long as 22 hours if I get too busy to eat. I have not tried running while fasting since I'm at work, but I will have to get pretty active with lifting and moving heavy items and never run out of energy.


      Now, all that being said, I do eat a rather low carb diet so I am often in a low level of nutritional Ketosis. When I get solidly into Ketosis I can just go and go. I have eaten a light breakfast then went for a 30-35 Mt bike ride on rough terrain. Something like that will take me ~4 hours. Afterwards I'll rarely have any energy problems and have even been able to get in a good lifting session before eating.


      So if you're putting yourself into Nutritional Ketosis, (running on fat) you're likely to feel plenty of energy.


      I don't run as much as I used to as I've switched back to biking.


        Thanks for your reply, confirms some of my thoughts!

          +! on nutritional ketosis. Been on KETO for 2 months, down around 12, with occasional IF for 16 hours. Havent noticed any decrease in performance for anything under two hours. Have yet to try something longer but excited to give it a whirl this season


            I don't think it work well on me. I've been doing IF for like a month and keep running in zone 2 hear rate according to my Garmin watch. But I do feel exhausted and craved for meal afterwards. I do cycling and weightlifting if I am not running. I am on 16-22 hours fasting, means 8 to 2 hours eating window? Did I do something wrong? I only lose weight in little amount.