Fasting and Exercise

The concept of exercising while fasting seems to be one of those topics that can quickly polarise people, with most falling on either the don't do it (it's bad), or do it lots (it's good).

As with most things I am pragmatic and say do what works for you :)

The common reason for exercising is based on the premise that in a time of calorie restriction (ie fasting), that exercising has two benefits over and above its normal benefits. Firstly, the calories expended have more value (ie as you are not eating you are creating a greater caloritic deficit when exercising than would be the case if you were not fasting), and secondly it is broadly assumed that your metabolism slows when fasting and exercise increases your metabolism.

There are bits of information coming out recently that indicate that your metabolism doesn't slow during a fast - at least within fasts of a certain duration (see this article: http://www.marksdailyapple.com/forum/thread29011.html - this was kindly sent to me by exercise and fitness guru Michael Rook). BTW MarksDailyApple.com is full of great information on exercise and the paleo lifestyle if you are so inclined.

So while I don't 100% buy into the metabolism slowing effects of fasting, I don't see any reason to curtail my exercising on days that I happen to be fasting. Just as I don't change my training plans if its raining, I don't change them if I am fasting.

Recently I completed a 108 hour fast (my longest to date - I will be posting an article at some point that details what I experienced day by day on that fast) during that fast which covered four full days, I did 2.5 hours martial arts one day, hiking in the brecon beacons the next, over an hour martial arts the following day, and nothing the final full day. These were the activities that I happened to have scheduled that week, and the fast just happened to align with it.

Experiment with the combination of fasting and exercise, determine what works for you, and above all have fun with it :)