I’ve fasted – like, just water and vitamins – for a week before.
I found that I was hungry, especially for about the first two or three days, but that I mostly ignored it after that, though I did find myself paying more attention to food ads and stuff like that than normal.
I was significantly cooler. I assume that the metabolism cranks down. I needed to wear heavier clothing than normal to feel comfortable.
I felt like I had less energy to effortlessly run around. Like, I could get up and go somewhere, wasn’t weak, just felt more like something you’d think about doing before doing.
Don’t need to hit the toilet much. That’s neat. Do need to stay hydrated, which I found to be surprisingly easy to forget about without sitting down for a meal.
I wasn’t trying to push myself physically while doing that, though.
I’ve also tried running a long-run calorie deficit where I wasn’t fasting, but also wasn’t eating much – something like 500 calories a day or less – for a longer period of time, for months, and then did a ten mile bike ride a day – there are calories coming in, but they’re considerably less than what you’re burning just living. I found the biking to be kinda rough. It just yanked all of the sugar out of my blood. Had a couple times doing that when I had my vision start to gray out at the end of my ride, needed to stop and get my head down. Was kinda like a zombie after my ride for a bit. Also was colder, just as when fasting. While it’s doable – I lost a bunch of weight doing it – I have to say that I think that it was rather harder than just outright fasting and not doing the exercise. Every time I ate, I felt like it kicked me back into “being hungry mode”, and it was only really physically a strain during the bike ride.
I had a harder time mentally concentrating on things when I’m doing that. Haven’t tried quantifying it, but I’d say that I was less-productive while doing that.
Interesting insight. If you were on a 500 calorie diet and “bonked” while cycling then presumably it was shortly after a meal, since at that level of calorie restriction you’re going to be running mostly on fat reserves directly rather than sugar via glycogen. It is absolutely possible to run marathons without having eating a gram of sugar. The advantage is precisely that you can’t hit a wall when the glycogen runs out. But apparently the keto diet is not quite as performant at the margin, which is why athletes haven’t all switched to it. It does deal with the hunger issue though, by all accounts.
I’ve fasted – like, just water and vitamins – for a week before.
I found that I was hungry, especially for about the first two or three days, but that I mostly ignored it after that, though I did find myself paying more attention to food ads and stuff like that than normal.
I was significantly cooler. I assume that the metabolism cranks down. I needed to wear heavier clothing than normal to feel comfortable.
I felt like I had less energy to effortlessly run around. Like, I could get up and go somewhere, wasn’t weak, just felt more like something you’d think about doing before doing.
Don’t need to hit the toilet much. That’s neat. Do need to stay hydrated, which I found to be surprisingly easy to forget about without sitting down for a meal.
I wasn’t trying to push myself physically while doing that, though.
I’ve also tried running a long-run calorie deficit where I wasn’t fasting, but also wasn’t eating much – something like 500 calories a day or less – for a longer period of time, for months, and then did a ten mile bike ride a day – there are calories coming in, but they’re considerably less than what you’re burning just living. I found the biking to be kinda rough. It just yanked all of the sugar out of my blood. Had a couple times doing that when I had my vision start to gray out at the end of my ride, needed to stop and get my head down. Was kinda like a zombie after my ride for a bit. Also was colder, just as when fasting. While it’s doable – I lost a bunch of weight doing it – I have to say that I think that it was rather harder than just outright fasting and not doing the exercise. Every time I ate, I felt like it kicked me back into “being hungry mode”, and it was only really physically a strain during the bike ride.
I had a harder time mentally concentrating on things when I’m doing that. Haven’t tried quantifying it, but I’d say that I was less-productive while doing that.
Interesting insight. If you were on a 500 calorie diet and “bonked” while cycling then presumably it was shortly after a meal, since at that level of calorie restriction you’re going to be running mostly on fat reserves directly rather than sugar via glycogen. It is absolutely possible to run marathons without having eating a gram of sugar. The advantage is precisely that you can’t hit a wall when the glycogen runs out. But apparently the keto diet is not quite as performant at the margin, which is why athletes haven’t all switched to it. It does deal with the hunger issue though, by all accounts.