I tried to search for this no luck, I may have done a poor job searching so I apologize if this has been answered.
Does anyone know if you eat your minimum amount of protein to maintain your lean tissue and your glycogen is depleted will the body use it for your lean mass before glycogen restoration?
I would think that if you are in ketosis the protein would definitely be used for lean tissue, and if you are a carb burner possibly for glycogen first.
Any thoughts?
@erdoke or @richard would know better than I - there are huge arguments about this all over, and few experts (as well as “experts”) seem to agree. The range is anywhere from 50 to 100g a day depending on the author in particular. I personally do not feel comfortable going under 50-65g a day regularly. I hover betwixt 70-100g/day on average. It also depends on the protein quality, too. Less insulinogenic protein is more desirable.
I think Lyle McDonald, who wrote one of the first widely-available books on it, touted a minimum of 50g a day after fat adaptation. I recall he stated during the first few weeks the protein requirement should be higher (I assume to avoid muscle depletion needing to fuel the brain with glucose (?) as there is no other energy requirement besides the brain that significant in the body), however he said after fat adaption, 50g/day was just peachy. However, I don’t recall much else. Hopefully others can give better input.
Jeff Volek found that low carb athletes maintained the same muscle glycogen levels (use and repletion) as high carb athletes while having a 2.3x greater level of fat oxidation. So we apparently prioritize repletion of muscle glycogen even when we are making the glucose from scratch and are otherwise glucose sparing.
That implies in both cases (carb burner and fat burner) the body would push glucose into muscle cells which would lower glucose levels and require more to be made. I’m not sure if the same is true for liver glycogen above the immediate requirements for the brain.
We often hear that protein isn’t stored, but about 1% of the protein in our body is labile - that is it’s being used for optional purposes that can easily be re-tasked. Another thing we can do in the short term is scavenge urea from the blood and make non-essential amino acids from scratch (de-novo genesis) - so there is some elasticity in supply. I suspect there wouldn’t necessarily be an immediate debt come due, but you would have to increase your intake of protein afterwards to repay that debt.