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by tim-fan 1068 days ago
I believe in some conditions fat and/or protein can be used to restore glycogen via Gluconeogenesis https://en.wikipedia.org/wiki/Gluconeogenesis

I remember reading that for keto diets it's important to not eat too much protein, otherwise the excess protein may be converted to glucose, replenishing glycogen and knocking you out of ketosis.

2 comments

From personal experience you’d have to eat a LOT of protein to kick you out. I do a pretty high protein keto diet and it works great. What really gets people is all the keto blogs talk about eating lots of fat. That great if you are doing keto for a lifestyle choice but if you’re doing it for weight loss you already have the fat and don’t need to boost your intake. Eating a fraction of the suggested macros still maintains satiety.
Gluconeogenesis can't really turn fat into glucose, humans lack a key enzyme for that.
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

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

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

Is there an obvious way to modify that ratio?
Protein gluconeogenesis is difficult and relatively minor in quantity.

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

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