Our last post described the evidence that the rate of gluconeogenesis (GNG) is stable under a variety of metabolic conditions.
We also described several experiments in which large amounts of protein were ingested or infused and did not increase the rate.
We concluded that eating more protein than your body needs probably doesn’t increase GNG.
Many of our readers expressed confusion about the implications of this finding, and our purpose in posting it.
The reason we investigated this was to address the following concern. One of the reasons keto dieters want to minimize the amount of carbohydrate they eat is so that their bodies don’t have to deal with excess glucose in the blood.
Whenever we ingest carbohydrate, it becomes sugar in the blood ¹.
Since blood sugar must be kept within a narrow range for safety ², eating carbs then causes the body to release insulin in order to draw sugar quickly and safely out of the blood and into storage (as fat tissue) ³.
In our opinion, the ideal situation is to introduce no significant amount of sugar into the blood by eating, and instead allow the body to supply the blood with just the amount of glucose it needs by producing it at a slow and steady rate through GNG.
This is achieved by keto dieters who carefully count any carbohydrates they eat, with the goal of keeping them below a certain level, for example, 25g per day.
Because some people have said that when you eat protein above basic requirements it turns into sugar, the question some dieters have is whether they need to count excess protein toward their carb counts ⁴.
They want to know if eating an extra 30 grams of protein means that they have added some 20 grams of sugar into their bloodstreams that now has to be dealt with just as if they had eaten 20 more grams of carbohydrate.
This is the conclusion we were setting out to deny.
Protein you eat in excess of your needs does not become extra blood sugar, unless you are severely diabetic.
However, this does not mean that eating too much protein has no adverse effects, or that keto dieters should be unconcerned about excess protein intake!
In particular, there is another important reason that keto dieters minimize the carbohydrate they eat — to increase the levels of ketones in the blood.
So a second question, and one that we did not address in the last post, is whether excess protein inhibits ketogenesis, the production of ketone bodies.
In contrast to the situation with gluconeogenesis, we suspect protein does inhibit ketogenesis.
If so, that’s a valid reason for not eating more than you need.
The major carbohydrates of the diet (starch, lactose, and sucrose) are digested to produce monosaccharides (glucose, fructose, and galactose), which enter the blood.
² Evidence type: authority
Marks’ Basic Medical Biochemistry: A Clinical Approach. Michael
A. Lieberman, Allan Marks. Lippincott Williams & Wilkins, Apr 21, 2008.
(Emphasis in original)
[I]nsulin and glucagon maintain blood glucose levels near 80 to 100 mg/dL, (90 mg/dL is the same as 5mM), despite the fact that carbohydrate intake varies considerably over the course of the day.
³ Evidence type: authority
Human Biochemistry and Disease. Gerald Litwack. Academic Press, Jan 4,
2008. p. 583
The anabolic effects of released insulin, after glucose is sensed by glucoreceptors of beta cells, are to cause the uptake of glucose and amino acids from the blood into muscle, and the uptake of glucose from the blood to form triglycerides in fat cells.
So I am trying to research a bit over the interwebs about just how much protein is to much and at what point your body will convert protein into glucose but there are so many different opinions on this… *pulls her hair out* This is where i think Calories in vs. calories out makes more sense… what yall think?
Is there a rule of thumb to what the bodies tipping point is for when it will convert protein into glucose?
muffin_maiden: I’ve read before that eating too much protein at once can cause it to turn to glucose, but how much protein can you eat before that happens?
I tend to eat two larger meals (or one big one) during the day with between 10 and 16 ounces of protein at a time.
Would that amount turn to glucose or are we talking that you’d have to eat a LOT of meat before that happens?
redtoile: Thanks for this post. I worry about this all the time.
CarolynF: According to Dr. Atkins, it is around 52 percent of protein gets converted to glucose.
So, if you overeat protein at each meal, it will act like carbs.