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Saturday, February 7, 2015

Intermittent Fasting and Running, Cycling

I have been doing Intermittent Fasting for about a month, figured I'd share some of my experiences.

If you're not familiar with it, check out my earlier post.

There are different ways to do it, I've picked the 16:8 method.  That is, fast for 16 hours and eat during an 8 hour window daily.

I'm also counting calories in an attempt to lose weight.  This tends to reduce that 8 hour window some days to a 7 hour window, and increase the fast length to 17 or even 18 hours.  But mostly my eating window is about 11:30am-7:30pm... or put more simply, don't eat after dinner and skip breakfast.

I have stuck to it pretty close to 100%, mostly because it's really quite easy once you get in the habit.  I rarely feel all that hungry at night or in the morning, and I find I have plenty of energy right through to lunch.


The only thing I struggled with at first is running in a fasted state.  That took some getting used to - but now I feel completely fine.  I had tried a 5km and 7km previously which went well, so today I tried to push it up to 10km.  This was in the 16th hour of fasting, it was totally fine, felt good.

I should note this was around LSD pace, I don't think running on empty is something that would maximize a tempo or interval run.  I'm not doing speedwork right now, but when I do I will do it at the end of the 8 hour feed period rather than in the fast period.


This is where my intensity has been.  I do my intense 1 hour indoor training rides in the evening, within an hour of supper (right at the start of the fast period).  This has been totally fine.

I tried to do a 2 hour ride with higher intensity last weekend really early in my feed period, which turned out to be a complete disaster... fell apart after an hour, just didn't have the energy.  I'm guessing this was related to diet, but who knows, not quite ready to conclude that on the basis of one bad ride.  I'm thinking pushing that back later in the feed time would be better.

Weight Loss

Intermittent fasting alone didn't result in me losing any weight at all.  It just stayed put.  It's entirely possible to overeat, regardless of how small that eating window is.

However it has worked very well with calorie counting, mostly because of the way you stop feeling hungry even when you haven't eaten in 16 hours.  It's remarkable.  That's really my biggest challenge when counting calories - the urge to cheat when my mind is screaming "eat! eat! eat!".  With Intermittent Fasting I don't feel that same urge.

Except.... when I have a couple beers.  That messes badly with both my hunger and willpower, and is still the weak point of my diet.  To that end I'm cutting out alcohol for a week, just to help things along.

But even without doing that, I'm down 5 pounds in 3 weeks.  Not quite the pace I had planned/hoped for, but still something I'm pretty darn happy with.  If that keeps up I'm totally content.

Good luck!

1 comment:

Anonymous said...

Keep going on the weight loss! 1 year ago I was a 235lb couch potato. I'm now a 172lb couch potato. I need to work on the latter.