Protein and Insulin

How Much Protein to Spike Insulin Levels

Insulin is a hormone found in the human body that is vital in the metabolism of carbohydrate, fat and protein. Insulin is considered a storage hormone. ItÕs main effect is to cause cells in liver, muscle and fat tissue to take up blood glucose, to stop the use of fat as an energy source and promote the storage of an energy surplus in the form of body fat.

Most people have heard and accept that glucose (sugar) can increase insulin secretion, what they don"t normally hear about is that eating protein can also increase insulin secretion.

In both young and old people, research has shown that 35 grams of casein (a protein typically found in milk) is enough to spike insulin after an overnight fast. 

35 grams of casein provides about 2.5 grams of Leucine and about 7 grams of branched chain amino acids. So this research is consistent with previous work showing that even small doses of branched chain amino acids can spike insulin.

This insulin spike from protein occurs very quickly after protein intake, typically reaching its peak levels at about 15 minutes after ingestion.

If we consider "fasting" insulin to be between 30 and 60 pmol/L, then 35 grams of casein is able to raise insulin out of the "fasting" range and into what is considered the "fed state" range (anywhere around 180 pmol/L)

However, 50 grams of protein from lean ground beef was found to only modestly increase insulin levels, leading to speculation that the type of protein may influence the insulin response. Interestingly, even though in this study protein caused insulin to increase only moderately, it did stay increased for more than 2 hours.

So although this insulin response was small, it was prolonged, and it was still enough to lower the amount of Free Fatty Acids (FFAs) found in the blood, signifying a move away from fasted state metabolism (using body fat as a fuel source). In fact, Free Fatty acids did not return to baseline levels until more than 3 hours after the protein was consumed.

The effect that protein has on insulin occurs in both the young and the elderly, and protein"s ability to increase insulin has also been found in diabetics.

In fact, while in non-diabetics the insulin response to protein is usually only 20-30% of the response you would get from an equal dose of glucose, in diabetics the insulin response to protein can be as high as 94% of the equivalent glucose response.

There are even some people that are sensitive enough to the branched chain amino acid leucine that dosing with leucine can cause hypoglycemia.

Bottom line - Protein can increase insulin in a dose dependent manner. How high your insulin will go depends on the type of protein and whether or not you are diabetic. In rare circumstances the amino acid Leucine can even cause hypoglycemia in some people.

References:

Dietary protein digestion and absorption rates and the subsequent postprandial muscle protein synthetic response do not differ between young and elderly men. Koopmen R et al. J Nutr 2009.

Effect of protein meals on plasma insulin in mildly diabetic patients. Fajans SS et al. Diabetes 1969.

Insulin response to ingestion protein in diabetes. Berger S et al. Diabetes 1966.

Comparison of Experimentally Induced and Naturally Occurring Sensitivity to Leucine Hypoglycemia. Knopf RF. J Clin Endocrinol Metab. 1963

EVIDENCE THAT INSULIN RELEASE IS THE MECHANISM FOR EXPERIMENTALLY INDUCED LEUCINE HYPOGLYCEMIA IN MAN. FLOYD JC. Journal of Clinical Investigation. 1963