Yesterday, I spent the whole day hiking/running 53 km in over nine hours. I followed the Davao-Bukidnon highway and I went as far as Los Amigos (Calinan) and then turned back following a trail that I used to take on my mountain bike (New Carmen and Magtuod). I wore a wide-brimmed hat and longsleeves to protect me from the scorching sun. I didn't have any breakfast or lunch (as usual). I didn't feel weak or tired. I didn't feel bored or lonely. I was back home in time for the afternoon mass which we celebrated in honor of St. Clement - a Redemptorist saint. Then I had a hearty dinner with the confreres.
How is it possible to hike/run the whole day without food?
I am used to fasting. When I was imprisoned during the early years of martial law I joined a hunger strike which lasted for a week and I didn't feel hungry. I am used to not eating for one week during Holy Week every year. I am used to eating one meal a day (that's what I have been doing for over a year). I have trained my body to subsist on less food.
A few months ago, I bought a book entitled "Warrior Diet" written by Ori Hoffmekler. The author argued that ancient hunters and warriors subsisted on one meal a day (usual at night). They spent the whole day either hunting or fighting and ate one heavy meal at night. They were more healthy and fit than those who ate three meals a day.
According to Hoffmekler, when we fast during the day, our body learns to use stored fat as fuel instead of glycogen from carbohydrates. Fat as fuel is inexhaustible, while glycogen can only last for three hours. During fasting, the body shifts to survival mode and becomes more efficient and alert. Eating during the day activates the parasympathetic nervous system and makes one sluggish and sleepy (thus, the need for siesta after a heavy meal). Whatever we eat cannot be immediately used as fuel. We can only use as fuel today what we ate last night and also the fat stored in our body.
So exercising while fasting is not just a matter of mind over body.
When I do my Tran-Mindanao Run-Hike two weeks from now, I will continue my practice of fasting during the day and eating only at night.