Gluconeogenesis

[Ioanna]

Is it or isn't it?

I guess I'd have to read something about the experimental conditions this cycle was discovered to make any half-way intelligent comment.

But, there is a magical number 58% I saw in Lex's journal referring to the percentage of dietary protein that can be converted to glucose (right?).  And Lex definitely did experience a correlation in the amount of protein consumed and blood glucose. So, seems to indicate that GNG does take place, at least when dietary protein is available... right?

So, if protein can be a glucose source (not saying this is at all healthy!!, just the sake of arguement) why would a 100% protein be so quickly so detrimental if enough water AND body fat are available to the consumer?  I could understand extreme sluggishness since protein is not an efficient energy source, but death in a matter of weeks... really?  Because if death can occur so quickly, wouldn't that suggest at least a very inefficient existence of GNG?

I'm not a bodybuilder, but isn't high protein what they do in the final week(s) before a competition to be really extra-super-cut?  And I'd expect the lower the bodyfat, the more dangerous such a diet composition would be.

[JaX]

gluconeogenesis is very ineffective and requires a lot of energy. As you mention, only part of the protein in a meal can be converted to glucose (58% being an estimate). This glucose is used by the body as energy to digest and break down the rest of the protein in the meal, which is not converted to glucose. But the body still needs energy to process and excrete the toxic byproducts of protein metabolism such as ammonia. Ultimately if the diet is too high in protein (and too low in energy: fats/carbs) there won't be enough energy to convert and excrete ammonia.

Ammonia is toxic to the nervous system and its accumulation rapidly causes death. Therefore it must be detoxified to a form which can be readily removed from the body. Ammonia is converted to urea, which is water soluble and is readily excreted via the kidneys in urine.

100% protein or even >50-60% protein by calories would be very deadly and would probably kill you faster than if you ate nothing (i.e. fasting). Survival experts recommend that even if you are starving in the wild you should not eat lean protein unless there is a water source and some plants (carbs) or fat. This corresponds with my own experience as the higher the protein in my meal is, the thirstier I am after. If I eat a lot of fat then I can go many hours after a meal without any water. Fat and carbohydrate metabolism have water as a by product while protein metabolism does not.

Bodybuilders  spend some weeks with a high protein diet and they still consume carbs in the form of grains. And I agree that the lower the bodyfat the more dangerous it is to go too high in protein. But high protein diets have been shown to, over the longer run, slow down the RMR (resting metabolic rate). Protein is the most inefficient energy source. Many low carbers say it speeds up metabolism and while it may do so initially the body and digestion eventually slow down.

[JaX]

Oh and a 100% protein diet would also be deadly because fats are required for the production of hormones

[lex_rooker]

Ioanna,
I think seeker pretty much hit the nail on the head.  Protein is the only macro nutrient that contains nitrogen.  Nitrogen is required to manufacture protein, but some of the byproducts of protein metabolism (like ammonia) are toxic in large quantities.  If we overdo on protein, we can overwhelm our body's capacity to remove these toxic metabolites.  Our liver, kidneys, colon, and skin all work constantly to remove waste materials from our bodies but like any machine, have a maximum capacity beyond which they can't keep up.

Our bodies need glucose at all times.  There are some systems that depend on glucose alone for fuel.  Our total glucose requirement is rather small, but it is necessary.  The clear lens of our eyes for example, depends on glucose alone for energy.  There are certain portions of our brains that also depend on glucose. 

Most body systems can use fatty acids or ketones for fuel, and actually prefer these over glucose.  The problem is that we overwhelm our bodies with so much glucose eating our high carb diet, that all systems that can possibly use glucose are forced to do so just to keep blood glucose from reaching toxic levels.   

As for your body builder question:  If large amounts of protein are consumed without enough fat or carbohydrates to moderate it, the body will pull the needed energy from whatever source it can to support the removal of the toxic nitrogenous waste products.  If there is body fat available it will this fat source until it runs out, and then "rabbit starvation" or protein poisoning will set in.  This is why body builders can get their fat reserves so low.  However, it certainly isn't healthy as far as I'm concerned.

Let's face it, we often do unwise things in an attempt to increase our own perception of beauty, be it botox, or body building and lowering fat reserves to the extreme. 

Lex

[RawpaleoHealthdiet]

actually to me surpise you can eat 100% protein and your body will use its own fat to compensate...it makes sense now. do not doubt this as its a survival mechanisims rabbit starvation can only occur once you have 0% body fat below 2% is deadly. I recommend eating all protein until body fat is 14%. Body fat is riddled with the toxins the body has tried to dilute. So you will get detoxed as well.