In my previous post (Low Carbs and Gluconeogenesis) I took a look at the low carb diet and Gluconeogenesis (GNG). The study found that GNG was increased by 14% in low carb diets. For folks who view GNG as the enemy that is challenging. After all, why go on a diet which makes your GNG even worse?
But, did you know that fasting increases GNG even more? This study looked at fasting and GNG (Landau BR, Wahren J, Chandramouli V, Schumann WC, Ekberg K, Kalhan. SC. 1996 Contributions of gluconeogenesis to glucose production in the fasted state. J Clin Invest. 98:378–385.):
The contribution of gluconeogenesis to glucose production was 47+/-64% after 14 h, 67+/-64% after 22 h, and 93+/-62% after 42 h of fasting.
It would be wrong to think this means we should get up in the middle of the night to eat in order to prevent GNG. We should not fear GNG since it is necessary. Our bodies produce the amount of Glucose that our bodies need for those parts of the body which require Glucose. When we are on Low Carb diets we produce Glucose in response to demand.
A more interesting question is why GNG is overdriven in Type 2 Diabetics. This is the paper for that subject (Song S, Andrikopoulos S, Filippis C, Thorburn AW, Khan D, Proietto J. Mechanism of fat-induced hepatic gluconeogenesis: effect of metformin. Am J Physiol Endocrinol Metab. 2001 Aug;281(2):E275-82.).
The high-fat diet increased endogenous glucose production (21.9 +/- 4.4 vs. 32.2 +/- 4.8 micromol x kg(-1) x min(-1), P < 0.05) and alanine gluconeogenesis (4.5 +/- 0.9 vs. 9.6 +/- 1.9 micromol x kg(-1) x min(-1), P < 0.05).
Excess supply of dietary fat stimulates alanine gluconeogenesis via an increase in fructose-1,6-bisphosphatase protein levels
Looks like substrate availability can increase GNG – when the substrate is fat.