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I find that physically you are fine when you do this: you can walk around, do house work, etc... but mentally you are shot. I would love to try this - but cert

by anonu 5y ago

I find that physically you are fine when you do this: you can walk around, do house work, etc... but mentally you are shot. I would love to try this - but certainly dont have 5 consecutive days where I can be a mental vegetable. The brain needs constant fuel. Anyone experience this as well?

pmulard 5y ago
I found my experience to be the opposite. I had clear mental focus, but felt physically drained of energy the entire time. I did a 3.5 day water fast, with the majority of my fluids from water/tea with salt for electrolytes. My sleep was pretty terrible up until the last night, when I got a solid 8 hours without waking up once. I usually wake up 8-10 times a night, so this was a huge breakthrough. I also regained my energy on that last half day and felt incredible. What type of fasting did you do, and what liquids did you drink?
arcticbull 5y ago
I generally find myself sharper, more alert and with much more energy. This continues the longer your fast lasts, up until day 7ish in my case. Your noradrenaline levels spike when fasting, and it can make it hard to sleep - too juiced haha. If you're finding yourself tired, it could be a lack of electrolytes. Try a teaspoon of salt in a pint of water. I tend to drink coffee when water fasting, which has an outsize effect.
- andai 5y ago
  Same. It makes sense to me intuitively: when you're hungry, you go into an alert "hunting mode". My sense of smell is normally very weak, but when I am hungry it increases by a factor of 100.
mcculley 5y ago
(Consider using “I” instead of “you”.) I have found that once I become fat adapted, I no longer suffer from mental clarity problems. It takes a couple of days without carbs to get there for me.
mrfusion 5y ago
Naps help. Plan your day around one or even two naps. Also watch your electrolytes. Salt, potassium and magnesium can greatly affect energy levels.
rhinoceraptor 5y ago
> The brain needs constant fuel. Anyone experience this as well? That is true, however that fuel does not need to be glucose. As far as I understand it, people eating 3 meals a day and snacks (all containing carbohydrates), their body is not used to relying solely on fat/ketones for energy, and it takes time to adjust. Also, it's very important when fasting to ensure you're replacing water and electrolytes since once you've burned through your stored glycogen you will have lost quite a bit of water. If you're feeling light headed or out of it, that is one of the causes, whether you're starting a ketogenic diet or fasting. When I'm fasting I use an electrolyte mix which has sodium, magnesium, phosphorus, potassium and calcium. One of the main reasons for refeeding syndrome is that electrolytes are depleted, and when someone eats again, their cells take up what little electrolytes are left in the blood, which leads to dangerously low levels.
- phonypc 5y ago
  To be precise, some of the fuel does need to be glucose. There is no such phenomenon as solely relying on ketones for energy, and the brain is especially glucose greedy. In a sufficiently fasted state, all of that glucose will be endogenously produced rather than coming directly from food, but it does need to be there.
  - techbio 5y ago
    Endogenously, from the fat/glucose pathway. Not sure that any glucose is required to be consumed directly. But we do love sweets, and fat cells love saving energy.
dlnovell 5y ago
I did a weekly "don't eat anything on Sunday and don't eat until Monday lunch" for about a year. Sunday afternoon/evening I'd be kinda groggy and grumpy. I'd wake up on Monday morning completely locked in - it felt like a high dose of adderol without ANY of the side effects. I'd get 2 days worth of work done in a morning. I'd always be bummed Monday afternoon because as soon as I ate the focus went away.
blastro 5y ago
In my experience, it seems the brain gets addicted to having a constant flow of glucose streaming into it (it's the most expensive organ to run, calorically) and it gets to think a lot more when it has its fuel. This isn't necessarily healthy, especially if left unchecked for a long period of time. Part of the benefit I believe I've gotten from fasting is re-training my brain to work well in a variety of glucose levels (including very low). These days, I can feel my body switch modes when I enter a low-glucose state. It's a certain type of relaxation that feels like my brain just stops running certain programs. For example, it can't afford to hold on to dramatic, powerful emotions in that low-fuel state, and so it stops running its "replay enraging memories" program, so to speak. You're correct that the brain needs constant fuel, but we have an unbelievable source of fuel in our bodies called fat. Increasing the metabolism's flexibility, such that it can gracefully tap into that massive fuel source, has had a noticeable impact on my mental and physical health. IME, it's more like a hump you have to get over, for what that's worth.
forgotmypw17 5y ago
It takes about a day for me to break through this. I do prefer resting physically when fasting, but the mental clarity is unparallelled after 24 hours.

by anonu 5y ago

pmulard 5y ago

I found my experience to be the opposite. I had clear mental focus, but felt physically drained of energy the entire time. I did a 3.5 day water fast, with the majority of my fluids from water/tea with salt for electrolytes. My sleep was pretty terrible up until the last night, when I got a solid 8 hours without waking up once. I usually wake up 8-10 times a night, so this was a huge breakthrough. I also regained my energy on that last half day and felt incredible. What type of fasting did you do, and what liquids did you drink?

arcticbull 5y ago

I generally find myself sharper, more alert and with much more energy. This continues the longer your fast lasts, up until day 7ish in my case. Your noradrenaline levels spike when fasting, and it can make it hard to sleep - too juiced haha. If you're finding yourself tired, it could be a lack of electrolytes. Try a teaspoon of salt in a pint of water. I tend to drink coffee when water fasting, which has an outsize effect.

andai 5y ago
Same. It makes sense to me intuitively: when you're hungry, you go into an alert "hunting mode". My sense of smell is normally very weak, but when I am hungry it increases by a factor of 100.

mcculley 5y ago

(Consider using “I” instead of “you”.) I have found that once I become fat adapted, I no longer suffer from mental clarity problems. It takes a couple of days without carbs to get there for me.

mrfusion 5y ago

Naps help. Plan your day around one or even two naps. Also watch your electrolytes. Salt, potassium and magnesium can greatly affect energy levels.

rhinoceraptor 5y ago

> The brain needs constant fuel. Anyone experience this as well? That is true, however that fuel does not need to be glucose. As far as I understand it, people eating 3 meals a day and snacks (all containing carbohydrates), their body is not used to relying solely on fat/ketones for energy, and it takes time to adjust. Also, it's very important when fasting to ensure you're replacing water and electrolytes since once you've burned through your stored glycogen you will have lost quite a bit of water. If you're feeling light headed or out of it, that is one of the causes, whether you're starting a ketogenic diet or fasting. When I'm fasting I use an electrolyte mix which has sodium, magnesium, phosphorus, potassium and calcium. One of the main reasons for refeeding syndrome is that electrolytes are depleted, and when someone eats again, their cells take up what little electrolytes are left in the blood, which leads to dangerously low levels.

phonypc 5y ago
To be precise, some of the fuel does need to be glucose. There is no such phenomenon as solely relying on ketones for energy, and the brain is especially glucose greedy. In a sufficiently fasted state, all of that glucose will be endogenously produced rather than coming directly from food, but it does need to be there.
- techbio 5y ago
  Endogenously, from the fat/glucose pathway. Not sure that any glucose is required to be consumed directly. But we do love sweets, and fat cells love saving energy.

dlnovell 5y ago

I did a weekly "don't eat anything on Sunday and don't eat until Monday lunch" for about a year. Sunday afternoon/evening I'd be kinda groggy and grumpy. I'd wake up on Monday morning completely locked in - it felt like a high dose of adderol without ANY of the side effects. I'd get 2 days worth of work done in a morning. I'd always be bummed Monday afternoon because as soon as I ate the focus went away.

blastro 5y ago

In my experience, it seems the brain gets addicted to having a constant flow of glucose streaming into it (it's the most expensive organ to run, calorically) and it gets to think a lot more when it has its fuel. This isn't necessarily healthy, especially if left unchecked for a long period of time. Part of the benefit I believe I've gotten from fasting is re-training my brain to work well in a variety of glucose levels (including very low). These days, I can feel my body switch modes when I enter a low-glucose state. It's a certain type of relaxation that feels like my brain just stops running certain programs. For example, it can't afford to hold on to dramatic, powerful emotions in that low-fuel state, and so it stops running its "replay enraging memories" program, so to speak. You're correct that the brain needs constant fuel, but we have an unbelievable source of fuel in our bodies called fat. Increasing the metabolism's flexibility, such that it can gracefully tap into that massive fuel source, has had a noticeable impact on my mental and physical health. IME, it's more like a hump you have to get over, for what that's worth.

forgotmypw17 5y ago

It takes about a day for me to break through this. I do prefer resting physically when fasting, but the mental clarity is unparallelled after 24 hours.