In the end I fasted for three and a half days instead of the four-day fast I originally planned. Sure I had to snack a bit, but I think I got the general idea. Here are my thoughts on the experience. (And here are my journal entries.)
The most remarkable thing was how unremarkable it all was. I didn’t have any trouble going 36 hours without eating. With only a couple of exceptions, I didn’t feel hungry at all. I know that sounds improbable, but it’s true.
The problem I had was headaches. My first one started about 24 hours into my fast and lasted until I had a little food 24 hours later. That’s a long time to have a headache, at least for me. 24 hours after that, my headache started to come back and I couldn’t sleep because I was so hungry. So I had another snack. On the morning of Day 4, I woke up with the beginnings of another strong headache, so I broke my fast.
Jess says I sounded stoned when she talked to me on Monday. Looking back, that sounds about right. I was foggy or a little dazed most of the time. My hands shook in the morning and I felt less coordinated than usual. I got lightheaded easily. It took me a long time to do anything that required moving. But at the time I felt fine. Just in slo-mo.
I didn’t feel lethargic while I was fasting, though. I went for a three-mile hike, and it felt good, although I did go back to my room and doze off afterward. Normally I run 3–7 miles every other day, but that wouldn’t be an option for me while fasting.
The biggest surprise for me was that, for the most part, my stomach didn’t feel empty. Most of the time I actually felt full. I’d heard that ketones (the fuel your body gets from fat while you are fasting) function as appetite suppressants, but I wasn’t expecting them to be quite so effective. I felt hungrier this morning than I did while I was fasting, and I had a hearty dinner last night.
The effects of fasting really became apparent when I ate breakfast yesterday morning. As the food hit my system, I could feel my body’s systems coming back online. It felt like I was waking up for a second time that day. Colors brightened, my mind clicked into focus, and the fog lifted. I don’t want to overstate the moment; it wasn’t profound or anything. But it was pretty cool.
I don’t think I will probably try long-term fasting again. If I am lucky enough to get another chance to spend a few days by myself, I’d like to be able to enjoy them by getting out and doing things. Also I’m just not curious enough to find out what happens if I fast for longer than three days. Fasting wasn’t a bad experience or anything, but I was a little out of it.
But I might try something similar. When I was fasting, my body was burning fat instead of carbs — ketosis, in other words. But you don’t have to fast to enter ketosis. You can do it just by cutting out carbs. And based on my experience, I think I could cruise for days on about 500 calories every evening while in ketosis. That would be just enough calories to give me a little energy boost, help me sleep, and stave off headaches, but not enough to fill me up. Those calories would also have to be mainly from protein and fat, not carbs, so as not to interrupt ketosis. (Once you consume enough carbs, you wind up in glycolysis again, which means you don’t get the appetite-suppressant side effect of ketosis.)
I might try that the next time I am on my own for a few days and can afford not to do much. But it’s pretty hard to be a good dad and husband when I am in a fog and low on energy. I’m not going to try fasting or radical calorie-cutting during my day-to-day life.
So that’s it. This morning I am packing up and heading home to go for a run and then see Jess and the girls. Thanks for reading!