Fasting + working out
This morning, 36 hours into a planned 42-hour fast, I went for a swim.
It seems completely counterintuitive to think of working out on an empty stomach, and yet I have to say that it was the best swim I think I've ever had: I was faster than usual, my muscles felt alive, and the time just flew by. When I realized it was time to get out of the pool or else be late for my first class, I actually felt a pang of regret and thought that I could have kept on swimming for a good while still. My swims are usually around an hour, sometimes more, sometimes a little less. After a night of tossing and turning, I slept through my alarm this morning and missed my bus and had to walk to the pool instead, so I didn't have as much time as usual. I still swam for forty-five minutes and came away feeling invigorated rather than my usual feeling of invigorated-but-tired. And then, instead of immediately heading home to eat breakfast, I went directly to work and didn't break the fast until several hours later - exactly as planned.
When I posted about it on facebook earlier today, as I usually do whenever I mention fasting, I received a concerned-sounding comment from someone, and while I was touched by the concern, it made me feel a bit frustrated all over again with how much misinformation there is out there on the subject of healthy eating, and healthy non-eating.
The fact is that working out in a fasted state is completely healthy. It's a good idea to first get your body into ketosis - a state of burning fat for fuel rather than relying on blood sugar (glucose, or stored glycogen which can be transformed into glucose). Exercising while fasting actually burns energy (whether through glucose or stored fat) is much more efficient, aka it burns through even more than it would otherwise. In addition, as my friend Marie-Sol just reminded me this morning, the body produces significantly more human growth hormone (HGH) while fasting, up to 300% more over a five-day fasting period (according to Dr. Fung). So, not only is it not harmful to work out while fasting, there are actually significant benefits to giving it a try!
Off to do my day's planks, and hope that my arms forgive me later!
It seems completely counterintuitive to think of working out on an empty stomach, and yet I have to say that it was the best swim I think I've ever had: I was faster than usual, my muscles felt alive, and the time just flew by. When I realized it was time to get out of the pool or else be late for my first class, I actually felt a pang of regret and thought that I could have kept on swimming for a good while still. My swims are usually around an hour, sometimes more, sometimes a little less. After a night of tossing and turning, I slept through my alarm this morning and missed my bus and had to walk to the pool instead, so I didn't have as much time as usual. I still swam for forty-five minutes and came away feeling invigorated rather than my usual feeling of invigorated-but-tired. And then, instead of immediately heading home to eat breakfast, I went directly to work and didn't break the fast until several hours later - exactly as planned.
When I posted about it on facebook earlier today, as I usually do whenever I mention fasting, I received a concerned-sounding comment from someone, and while I was touched by the concern, it made me feel a bit frustrated all over again with how much misinformation there is out there on the subject of healthy eating, and healthy non-eating.
The fact is that working out in a fasted state is completely healthy. It's a good idea to first get your body into ketosis - a state of burning fat for fuel rather than relying on blood sugar (glucose, or stored glycogen which can be transformed into glucose). Exercising while fasting actually burns energy (whether through glucose or stored fat) is much more efficient, aka it burns through even more than it would otherwise. In addition, as my friend Marie-Sol just reminded me this morning, the body produces significantly more human growth hormone (HGH) while fasting, up to 300% more over a five-day fasting period (according to Dr. Fung). So, not only is it not harmful to work out while fasting, there are actually significant benefits to giving it a try!
Off to do my day's planks, and hope that my arms forgive me later!
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