[arcticbull]

This is not accurate. If that were true people who fasted would die after about 3 days, but of course, the longest fast lasted about 350 days. The reality is after 3 days of fasting, your blood glucose level stabilizes. Your body must perform gluconeogenesis to survive because a few types of tissue require glucose to live - those without mitochondria. This means red blood cells and about 30% of the energy requirements of your brain.

Pathway is here if you're curious. [1]

[1] https://en.wikipedia.org/wiki/Gluconeogenesis

[Blackthorn]

There's the glycerol part of the fat, sure. But your body can make glucose from a lot more stuff. Namely, proteins.

[arcticbull]

I think when people say "fat" they mean triglycerides - not free fatty acids - which includes the glycerol backbone. So it's not right to say that humans can't turn fat into sugar, they can.

Per the wikipedia article 90% of gluconeogenesis happens from lactate, glycerol, alanine and glutamate.

[Blackthorn]

Yeah, fair enough. That'll maybe teach me to not type abbreviated nonsense on my phone.

[Aerroon]

>Per the wikipedia article 90% of gluconeogenesis happens from lactate, glycerol, alanine and glutamate.

That's interesting! Glutamine vs glutamate ratio is supposedly something that affects motivation.[0] I wonder if (enough) gluconeogenesis thus boosts motivation?

[0] https://www.nature.com/articles/s41386-020-0760-6

[wuiheerfoj]

Is there an obvious way to modify that ratio?

[Aerroon]

The "word on the street" is that oral glutamine supplementation works for this purpose. My personal experience agrees with this (but the effect probably isn't very large).

In the morning I mix a tablespoon of glutamine into a glass of water and drink it. You can buy glutamine in supermarkets next to all the other protein supplements (glutamine is the most abundant amino acid in the body).

It's also helpful to your immune system.

---

That being said, that's 'hearsay'. I am not aware of any studies that show that oral supplementation of glutamine improves motivation. That might just be due to time though. The original study showing that glutamine-to-glutamate ratio in the nuclear accumbens affects motivation was published in 2020.[0]

We do know that glutamine does pass the blood brain barrier.[1] There's probably a decent chance that oral supplementation of glutamine works.

Some downsides: it can make seizures worse. There's some worry about it having some effect on cancer, although that seems to be mixed - some seem to think it would increase the risk of cancer, others say it decreases it (cancer cells use glutamine as fuel).

[0] https://www.nature.com/articles/s41386-020-0760-6

[1] https://pubmed.ncbi.nlm.nih.gov/12933350/

[dbcooper]

Protein gluconeogenesis is difficult and relatively minor in quantity.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3636601/

[Blackthorn]

That's not what that study says. That study is about dietary protein.