I can't seem to find an answer to a question I'm mulling around in my mind.
Anyone have any insight?
Here it goes:
When on a low carb diet, often times you will convert protein into glucose through a process called gluconeogenesis.
So even if you're not directly eating glucose, you will most likely "manufacture" it through protein.
Will this extra glucose increase insulin in your blood?
Theoretically I would think it would... But I can't seem to find any information on it.
This is interesting to me because it seems that even if you are trying to minimize blood sugar, and/or insulin... you may not be able to directly influence it as much as you think you can.
But maybe gluconeogenesis happens at a slow enough rate where it keeps insulin/glucose levels constant and low.
Maybe that's one of the big benefits of low carbs. Not that you don't have carbs in your system, but that it slows down the rate of glucose being put into your system.
And maybe that's why eating fruit is better than a soda because of the extra fiber that slows absorption.
Anyhow, I'm going a bit off topic here.
But does anyone know how Gluconeogenesis effects insulin levels?
Thanks for posting this question, I am curious as well. I did read about this last week in a blog, but my vapid brain forgets exactly where the details of this exact topic is located....
I'd trust the body to make just the right amount of glucose from Prima/Paleo food sources. There is new science to suggest (Gedgaudas' "Primal Body, Primal Mind") that limiting protein to the very smallest amount needed for the body's structural needs, can extend life spans a bit through down regulating a metabolic process called mTOR. So in essence we can "cheat" and refine our intake of Fat, Protein, and Carbs to optimize our health and longevity.
My personal hunch is that eating Primal/Paleo foods strictly, perhaps better than the 80/20 rule, can result in an optimal human diet and the nuance of limiting/regulating protein to that most detailed measurement is not necessary, but could have some benefit.
But I certainly would never say "all things in moderation!" From reading Peter at Hyperlipid, and Gedgaudas' book, I am shooting for a 70-80% fat, 20-15% protein, 5-10% carb intake day to day. And focus on 100% Paleo/Primal compliance, as well.
But indeed, the human animal has no need for dietary carbohydrate for a healthy and vibrant life.
Gluconeogenesis is a necessary process if you're not eating carbs, as there are tissues in your body that require glucose (red blood cells). It's not a particularly overactive process, and tends to top out at around 200g/day of glucose (note that it can use the glycerol after it breaks off fatty acids from a triglyceride too, so just having body fat will let it make glucose). It's not going to cause huge insulin spikes and so on, and it will tend to be regulated close by glucagon in response to a need to bring blood sugar up to required levels, rather than moving them from normal to high.
Protein does cause insulin and IGF1 release, and those hormones both activate the PI3K/Akt pathway, which ends up activating mTOR (mammalian target of rapamycin, kind of a misnomer since rapamycin does other things too, but it does inhibit mTOR). mTOR has two partner molecules, Raptor and Rictor. Both share a few things that activate them and inhibit them (insulin stimulates them, curcumin (active ingredient in turmeric) inhibits both), but they do different things. mTOR/Raptor stimulates protein synthesis in response to sensing dietary protein, which is an important mechanism. mTOR/Rictor stimulates full activation of Akt, which is necessary for growth, but excessive Akt activation is also involved with cancer (mice with Akt turned on all the time tend to die of cancer pretty young).
Anyway, it's not quite as simple as it's been made out to be, as these pathways are critical for doing things like taking the protein you eat and using it, and if you are physically active or strength training or injured/recovering from surgery you may need more protein than the minimal 75-80g/day as near-term concerns trump vague concerns about life expectancy at that point. If you stay away from carbs, don't eat more protein than you require, and maybe eat some turmeric-rich curry, you will probably have some effect on your statistical lifetime, but I don't know how large it would be.
Note that if you get cancer for whatever reason, you should keep this in mind. Keeping protein low will inhibit mTOR/Akt in the cancer cells too, and filling the rest of your dietary needs exclusively with fat will limit the cancer's growth, because most cancers tend to switch on anaerobic glycolysis and burn glucose very inefficiently but in a way that allows for rapid growth (one of the reasons people tend to lose weight when they have a tumor..it's consuming all their fat stores by burning them for 2 ATP/glucose instead of 36 ATP/glucose).
Also remember to fast before your chemo for 24-48 hours, as it'll activate a cellular mode called 'autophagy' where cells clear out old misfolded proteins and are less susceptible to damage (and therefore consume fewer repair resources during starvation) -- the cancer cells will not enter autophagy and the comparative damage of the cancer relative to the healthy cells will be much larger. Clearing out all those old proteins seems pretty necessary and is one of the possible sources for the health benefits of intermittent fasting.
Okay, husband of biology Ph.D. rambling over.
Nick, now THAT'S a reply! THX!
Nick and Acmebike,
Thanks for your responses!
That was awesome
So I understand that in a glucose limited environment, the body will manufacture what it needs, and when it needs it. This would indicate that it's regulating it's glucose levels at an "ideal" rate.
Now the next question I have is...
Does pre-existing glucose levels and/or insulin levels influence gluconeogenesis?
Basically, if you already have glucose/insulin in your blood from eating something with glucose limit gluconeogenesis?
And if so, does that free up extra protein? And would that then help preserve and/or build muscle?
Also, if you eat only small quantities of glucose, would it basically equal the overall effects of gluconeogenesis in regards to blood glucose/insulin levels?
Basically 15 grams of protein converting to glucose in your blood vs. 10 grams of glucose eaten orally.
What's the real difference?
Other than optimal nutrient timing? (Your forcing glucose into your blood orally vs. letting your body convert protein go glucose when it needs it.)
The mind... it asks me so many questions
Insulin should shut down glucose production by the liver; glucagon will stimulate it. So yes, if you raise your blood sugar via food intake, it will slow down or stop gluconeogenesis. If you were breakdown protein to turn into glucose, then yes, it would make extra protein available.
However, using protein for glucose presents a nitrogen disposal problem, and is less efficient than using the glycerol off the fat it's breaking down anyway. Additionally, lactate produced by your body due to anaerobic metabolism can be reformed into glucose (red blood cells produce lactate from glucose via glycolysis, which can then be recycled in the liver back into glucose).
Not all amino acids can be turned into glucose (some can only be turned into ketone bodies, but some can go both ways), but the big ones we get in meat can (glutamine and arginine).
If you eat a bunch of protein, your gut will slow down gastric emptying and peristalsis so it can take longer to digest the meal than if you had eaten a potato. The potato will get dumped very quickly into your blood as glucose, whereas the protein will trickle out more slowly as amino acids, making it more possible to use them for what they're best at (making new proteins). The process of gluconeogenesis is, again, responsive to glucagon and insulin, so if you have a functioning pancreas sending out those signals to the liver, it will only produce glucose in response to a deficit in blood glucose as expressed in higher glucagon and lower insulin by the pancreas. Likewise, if you already have high blood glucose, your liver will response to the high insulin and low glucagon by producing fat from the glucose the muscles and other tissues don't uptake. This is why you have high triglycerides if you eat a bunch of carbs all the time.
In other words, if you eat protein, the liver will only turn it into glucose as needed, in attempting to keep blood glucose from getting too low. Obviously if your liver and other tissues become insulin resistant this may not work quite the way it was intended, resulting in high blood glucose. But in a normal healthy person, eating protein will not ever cause your blood glucose to go much above nominal on its own. And it's probably going to preferentially use sources of lactate, then glycerol, and then protein, in order to do that, which is why you generally only get the ammonia breath/pee and protein catabolism after a long abusive cardio bit.
The potato, on the other hand, proceeds in fairly quick fashion into the blood, regardless of your existing glucose level -- the intestinal wall just isn't as smart as the liver or pancreas. Which is great if you're approaching hypoglycemia because you're a diabetic, or if you have drained a lot of muscle glycogen and have insulin sensitive muscles that will suck all of it up without storing any as fat, but for most people is not so good.