Insulin is a protein hormone that is released by the Pancreas in response to elevated blood glucose levels. Elevated blood glucose levels are a result of ingesting food, and different types of food will cause different increases in blood sugar. For example, carbohydrates can elevate blood glucose levels up to ten times its normal amount whereas proteins and fats can cause blood glucose to rise two to three times the norm. The amount of Insulin secreted by the pancreas is influenced by the rise in blood glucose: the higher the blood glucose the higher the secretion of insulin.
What does Insulin do?
Once secreted into the blood stream, insulin will help glucose travel into the liver, skeletal muscle, and adipose tissue. Glucose is stored as glycogen in the liver and skeletal muscle for energy and as fatty acids in adipose tissue. Skeletal muscle contains approximately 500 grams of glycogen and the liver approximately 100 grams. The higher the blood glucose level, the more will end up in adipose tissue if glycogen stores in the liver and skeletal muscle are full.
As stated above, different foods have different affects on blood glucose. The glycemic index ranges from 0 to 100 and is a measure of a foods affect on blood glucose. The higher a food scores on the glycemic index, the greater affect it has on blood glucose. For example, wheat bread scores 80 and broccoli scores 10.
HyperInsulinemia and Insulin Resistance
If we are continually consuming foods that elevate our blood glucose, our cell receptors become less sensitive to insulin. This means the pancreas has to secrete more insulin to drive glucose into the liver, skeletal muscle, and adipose tissue.
Chronic elevation of insulin in the blood stream is known as hyperinsulinemia. Hyperinsulinemia can cause the liver to continuously uptake glucose, resulting in increased glycogen stores but also increased fatty acids. Increased liver fat increases risk for fatty liver disease.
If chronic elevation of insulin persists long enough, cells become resistant to insulin. This is type II diabetes. When the liver becomes resistant to insulin and its glycogen stores become depleted, it will start releasing LDL particles and triglycerides into the bloodstream. This can pose long term risk for atherosclerosis (hardening and narrowing of the arteries) and stroke.
Having diabetes doubles your risk for Alzheimer’s disease
The prevalence of type II diabetes has tripled in the past 40 years
According to David Perlmutter, author of Grain Brain: “In 1994 when the American Diabetes Association recommend that Americans should consume 60 to 70 percent of their calories from carbohydrates, rates of diabetes exploded. In fact, the number of cases of diabetes in this country actually doubled between 1997 and 2007.”
The CrossFit prescription is intended to help combat the metabolic derangement that can result from chronic elevation of blood glucose and insulin:
“Eat meat and vegetables, nuts and seeds, some fruit, little starch, no sugar. Keep intake levels that will support exercise but not body fat.”