Where does energy come from during a fast?

[atomicspacebunny]

The 50 day guy reported a beginning body fat of 29.2%, “as recorded by a personal bioelectrical impedance device.” After 49 days he was measured at 19.8% body fat. If we accept those figures, that’s losing 0.6 lbs of fat per day.

The readings could be from the day before also?

Most body fat oxidation occurs during sleep according to this Respiratory Quotient (RQ):

“…During sleep, the CMRglc decreases much more than does CMRO2. Moreover, the transition into sleep is accompanied by a reduction in whole-body RQ. These findings suggest that the brain, like the rest of the body, shifts towards oxidation of fatty acids and ketone bodies released into the circulation during this period. …” …More

image link

I notice that FFA bump then the ketones following on its heals.

Blood Metabolites:

image link

Also seems during waking hours we burn exclusively glucose or creatine?

Richard also has a post on the forum (somewhere?) about how much body fat it is possible to burn per day in contrast to a “…maximum rate of body fat use is 31 kcal per pound ?”

[ellenor2000]

Also seems during waking hours we burn exclusively glucose or creatine?

That could be true, but it would make no physiological sense.

[atomicspacebunny]

but it would make no physiological sense.

The DATA?

[ellenor2000]

You capitalise data like it’s an acronym. It’s not. Don’t do that.

I’m just gonna say citation needed on what sort of “data” you mean and mute this thread.

[atomicspacebunny]

If your using muscle while awake your going to use more stored glycogen (glucose) even with simple daily tasks?

The brain of course will be powered by the liver but with more glucose than ketones, too much glucose and the brain will make fructose to give back to the liver which is strange?

[atomicspacebunny]

You capitalise data like it’s an acronym. It’s not. Don’t do that.

I’m just gonna say citation needed on what sort of “data” you mean and mute this thread.

Do have any DATA to support what does not make “physiological sense,” you have to have a reason from somewhere and was wondering what your source of information is?

Phinney and Volek do not even know with all their research?

[atomicspacebunny]

Don’t do that.

Don’t ever tell me what do my friend!

[Mavro]

Wow, Vegan, record holding weight lifter that eats OMAD. Talks about autophagy and the importance of meal and exercise timing is important to his way of life. Relies on his body recycling his proteins to stay youthful. Very interesting.

[Mavro]

I agree with there being a very limited amount of research. I guess without food company funding, that makes it hard

My gut feeling is that if somebody was truly pushing it while fasting, exercising to the point where they ‘hit the wall,’ had a ‘hard bonk,’ etc. - really felt like the energy tank was empty, that on subsequent days it would get progressively harder. I doubt the body would entirely recover by the next day. I’m assuming that glycogen would be well depleted along with whatever “easy access” fat there was (as opposed to the “difficult access” stuff the body uses after that point just to maintain life). It might feel like that too, i.e. "I’m staying alive, but that’s about it… " “Easy/difficult access” is just a guess on my part how it’s working; nothing official or agreed-upon there.

For a non-athlete such as myself, I think you are correct. I noticed for myself on a 7 days fast that I had energy to spare on day 3, but when I worked out again, I did a lot less 2 days later. Mind you, I didn’t discover that I needed to add salts so that was likely a factor. But I think that you’re right.

It looks like the story is different for athletes. The FASTER study mentioned above is concluded the following:

Compared to highly trained ultra-endurance athletes consuming an HC diet, long-term keto-adaptation results in extraordinarily high rates of fat oxidation, whereas muscle glycogen utilization and repletion patterns during and after a 3 hour run are similar.

I have a long ways to go. But I’ll just KCKO!

[PaulL]

It’d be nice to know the ratios of fat to nonfat tissue. But just as a guess, if there’s a generalized expectation of losing 0.5 to 0.6 lbs of fat per day while fasting, maybe a little more for bigger people, then that looks pretty good.

I think a certain amount of muscle loss, simply from having less fat to haul around, would be healthy. Enough muscle loss to qualify as “wasting” probably wouldn’t be. Have you read the case report on Barbieri? I believe they measured some of this, but I lost the PDF in a computer accident and haven’t been able to find it online again.

[MarkGossage]

Was it this one?

postmedj00315-0056.pdf

[OldDoug]

Mark, I get an error for that link. Even the NIH link online does it.

https://pmj.bmj.com/content/postgradmedj/49/569/203.full.pdf

I think a certain amount of muscle loss, simply from having less fat to haul around, would be healthy. Enough muscle loss to qualify as “wasting” probably wouldn’t be. Have you read the case report on Barbieri? I believe they measured some of this, but I lost the PDF in a computer accident and haven’t been able to find it online again.

Paul, it doesn’t say much about lean tissue loss. When he was done fasting, he was fairly ‘normal’ but I have no idea how strong he really was. That’s wild, losing over half one’s weight. The legs and back would think it’s a whole new world.

[Polly1]

Interesting and may be geographical, but Mark’s link works for me.

[MarkGossage]

Hmm both links work for me…

I’ll post this article which also has a link so you can see if that works.
Otherwise I can screenshot it and send it to you if you’d like?
M
https://cristivlad.com/total-starvation-382-days-without-food-study/

[OldDoug]

It works perfectly for me now, Mark. I wish we’d have another such fast, rigorously studied, today.

[PaulL]

Yes, Mark, that’s it. Thank you!

[ElmosUzi]

a 30 hour one literally made me diabetic (I’ve heard all of the shit about that being normal, and I don’t buy it)

A 30 hour fast??

[atomicspacebunny]

His blood glucose hovers around the 30’s, this is just a shot in the dark but I wonder if that is what normal should be if you lowered the sodium.

Human body only needs 0.5 grams/500 mg. of sodium a day. Any more could be is toxic.

[Janie]

a 30 hour one literally made me diabetic

So not eating for 30 hours caused your blood sugar to be permanently high immediately after that and never came back to normal for an extended period?

Or do you have a different definition of diabetic?

Sorry this happened to you - must have been scary.

[OldDoug]

His blood glucose hovers around the 30’s, this is just a shot in the dark but I wonder if that is what normal should be if you lowered the sodium.

Human body only needs 0.5 grams/500 mg. of sodium a day. Any more could be is toxic.

If that’s our old buddy Angus, then yes - he really went along quite low for a long time. That one reading at 17… For fans of the other measure, that’s just under 1 mmol/L.

Sensitivity to higher intake of salt only affects ~25% of the population. For the rest of us, barring kidney trouble or a few other things, it’s usually not a big deal, as long as we get enough.