Blood Sugars Go Up After Protein

In many (maybe even most) people blood sugar levels often goes up by a small amount following consumption of protein. I did an experiment which showed this in myself (Blood Sugar Responses Compared). This effect is temporary and the levels often go lower after a few hours than before the protein was eaten.

This increase of blood sugar is actually a good thing. It indicates that your body is spending a lot of energy on Muscle Protein Synthesis. Muscle Protein Synthesis has a 3 hour window after eating protein (MPS peaks at 90 minutes and returns to baseline in 3 hours) (Protein Guru). This is similar to the effect from exercise where your blood sugar will go up immediately after intense exercise – even when you are fasted. Your body is mobilizing energy in the form of glucose from the liver (Protein Gurus – Part 2).

Contrary to a lot of misinformation out there this is not Gluconeogenesis (GNG) from the Protein. It is GNG that comes from the fat in your liver and bloodstream (Xinhua Chen, Nayyar Iqbal, and Guenther Boden. The effects of free fatty acids on gluconeogenesis and glycogenolysis in normal subjects. J Clin Invest. 1999 Feb 1; 103(3): 365–372.).

This is basically the same as exercise where your blood sugar goes up with intensive exercise but if you look at the glucose levels over time they are lower averaged out over the entire day from higher protein consumption. This has been demonstrated through CGM.

GNG from your liver comes from the glycogen already in your liver which came from the fat in your bloodstream and liver. And believe me, we all need lower fat in our livers. That’s the main cause of T2D (in my opinion and that of many others).

If you are low carb your body has to produce glucose to make up for what you are not getting in your diet. Your body can produce glucose from any of the three – Carbs, Protein, and Fat. The body is really bad at doing it from Protein but if you only ate Protein and you ate an excessive amount the body would be forced to use Protein to make the needed glucose.
What is not commonly appreciated is that the liver only produces the glucose that it thinks that it needs. It’s not producing based on what you eat (outside of carbs). When you eat protein your body needs more energy to perform MPS so it sends up the glucose a small amount. Glucose for muscle building is a good thing.
Carbs, on the other hand, send up blood glucose by a large amount and are not a good thing when it builds up.

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