The FastDay Forum

[carorees]

Surprisingly, perhaps, on fast days people tend to feel more energised rather than weak and feeble. Therefore, the question arises as to whether it is OK to exercise on fast days.

The short answer is yes, its fine!

This is what Michael and Mimi have to say about it in their book:

"Research demonstrates that even a more extreme three-day total fast has no negative effect on the ability to perform short-term, high-intensity workouts or long-duration, moderate-intensity exercise. Athletes seem to suffer no loss in performance during occasional fasting; a 2008 study of Tunisian footballers during Ramadan found that fasting had no effect on performance ... training while fasting can result in better metabolic adaptations (which means enhanced performance over time), improved muscle protein synthesis, and a higher anabolic response to post-exercise feeding. Training on an empty stomach turns out to be beneficial on multiple levels, coaxing the body to burn a greater percentage of fat for fuel instead of relying on recently consumed carbs; if you’re burning fat, don’t forget: you’re not storing it."

From: Mosley, Michael; Spencer, Mimi (2013-01-10). The Fast Diet: The secret of intermittent fasting – lose weight, stay healthy, live longer (Kindle Locations 1257-1260). Short Books Ltd. Kindle Edition.

I might have to try exercising on a fast day next week and see how it goes. Normally I work out just before lunch, but if I get a late start I need to eat lunch first and then work out because I usually deal with limited cafeteria hours. Yesterday (day after fast day) I ate way too much for a pre-workout meal and that was kinda painful...

Working out on a fast day would, since I bring my tiny lunch to work instead of going to the cafeteria, give me a little more flexibility on when I work out. I'll see if the energy levels are good -- especially the energy levels for the last 4-5 hours of working after the workout and the rest of the night.

[carorees]

I imagine that our caveman ancestors were mainly going hunting on an empty stomach because if there was plenty of food available they likely didn't need to hunt!

Do you exercise on fasting days? It is a slightly different question!
I struggle to exercise at all and have avoided fast days (which means I've done nothing).
My husband feels he ought to exercise on feed days, so he goes to the gym and I stay home with kids. I could go to Zumba or Bokwa classes on a Wednesday evening when he is home - but it is my fast day!

[carorees]

I do exercise on fasting days...if you can call 5 x 30 secs flat out biking exercise! But Dr M says that this regime brings substantial benefits.

I excercise quite a bit (30 day chred and I run 10-12 miles per week) I'm just going to carry on as normal until my body tells me to stop!

I rane for 3 miles onboth my Fast Days last week and felt fine. Probably even better than I usually do and it killed my appetite.
Strangely, I found my usual weekend 6 miles a lot harder and I had eaten normally for two days before.

I exercised today on a fast day to try it out. Everything felt fine. I thought the low calories since then would make me tired and/or extra hungry compared to the last fast day where I didn't exercise, but in fact I find I'm alert and not sore and my appetite was suppressed for about an hour after I was done exercising (and I hadn't eaten anything in the morning before exercising, waiting until lunch to eat).

I also tried something new today with my run (treadmill) where I ran a light-to-moderate pace for about 25 minutes or so, and then in the last 5 minutes I jacked it up for 3 separate 20 second high-intensity sprints with a healthy angle, separated by walking for about 2 minutes in between. That was based on that Dr. Mosely BBC Horizons special on exercise that talks about 3 minutes per week of high-intensity exercise.

Might as well try it all!

I exercise on fast days spin class and feel great.

I exercise on fast days. Well sometimes, not when it's snowing. I usually run for about 30-45 mins and haven't had any problems doing this on a fast day.
One word of warning, the study you quoted involved athletes, so very fit individuals who were accustomed to exercise and presumably accustomed to exercising during as fast. The general population might not respond the same way.

I run with a running group and am usually somewhere in the middle of the pack as far as speed is concerned. I had some worries about running on a fast day but actually ended up near the front! I know this could be coincidence and will have to see how it goes in the future but I certainly didn't feel like it was any harder.

You may find the following link interesting. It looks at the experiences of some folks, including a dr, doing various forms of IF. The link will take you directly to the page on 5:2 and exercising. Interesting comments at the bottom too.

http://www.precisionnutrition.com/inter ... /chapter-5

When exercising do you still stick to the same calorie intake on fast days? For instance it's fast day for my wife and she has just done a gym class where she burned 200 calories so should she allow an extra 200 calories or stick to the 500?

The short answer Tony is that you should stick to the 500. You don't need any more! I find that exercising on a fast day actually suppresses my appetite.

Okay thanks I thought that was the case.