I seem to recall, and need to look It up, that Dr. Tro Kalayjian, Low Carb MD podcast host, has questioned Dr. Gardener’s controlled nutrition trials. Dr. Gardner has done nutrition controlled trials. That gives him more kudos in data, and maybe findings, in my opinion, than Harvard epidemiologists.
My current understanding is that gluconeogenisis GNG is a demand driven process in a low carbohydrate metabolic environment.
However, is like saying but. Increased protein that is digested and absorbed into circulation as amino acids produces a higher availability of ATP cellular energy, increased cell structure building blocks (I wonder if intracellular organelles increase, like an increased number of mitochondria in muscle cells?) and, eventually in spill-over excess, hydrated carbon level when the unused amino acids are transaminated, deaminated, and/or carboxylated in the liver and kidney and the carbon chain base either forms; simple carbohydrates, ketones, fatty acids, and with ammonia, NH4+, being excreted as waste from the body in the urine. Ammonia is toxic in your body but is marvellous in the garden.
Go pee in the garden if you are on a higher protein dietary intake.
Is GNG switched on in the presence of excess circulating glucogenic amino acids that have no place to be used or stored? Even in a low carb internal body environment.
So there is evidently a protein threshold before we see the higher blood glucose evident for many people that follow a low carb higher protein way of eating.
Controlling protein inputs is a logical thinking step for those interested in the physiology and biochemistry. Controlling protein inputs seems like something a person can do to tweak their eating to control blood glucose, or to lift blood ketones for therapeutic effect. That’s why we’re here in the forum.
There is an output human behaviour controller available as well. And Dr. Gardner does speak to it in the interview. If a human is growing they have an increased protein requirement over and above the 1g/kg per day. Growth states in humans, for example, are: children, pregnancy, and muscle building exercise.
So, @lfod14 is correct, I think, on quite a few things. If we are building lean body mass, including muscles, from regular activity and load bearing exercise, there will be an increased protein usage and requirement, when compared to a sedentary university academic at a computer keyboard.
So, when we feel naturally compelled to be active, to exercise, to move and lift things, to reorganise the garage, when we go into nutritional ketosis, and we have lost enough excess body fat to reduce the risk of injury, then we will gain lean body mass and muscle, requiring enough dietary protein to do so.
The thought train will pull into a stop here.
Next thoughts are: there are ketogenic amino acids and glycogenic amino acids. Who is whom? Where are they found in foods? I’m thinking glycine for one, but Dr. Gardner also mentions methionine and lysine (as deficient in a vegan way of eating). (Side trail is lysine is the treatment for ‘cold sores’ caused by herpes. Maybe vegans don’t get kissed as much as omnivores?)
Here is a high level basic reference I’m using: