It was used to be thought that the brain was not affected by insulin. This belief was based upon a false assumption that there were no insulin receptors in the brain. However, insulin receptors have now been discovered in nearly every region of the brain, especially those regions in charge of controlling appetite. In insulin-sensitive people, a rise of insulin after meals results in a promotion of satiety through its action in the brain. However, in those with insulin resistance, even the excessive insulin levels experienced after meals no longer result in a significant sense of satiety.In normal individuals, it has been shown that regions of the brain responsible for appetite regulation respond to after-meal elevations in insulin by significantly increasing their intake of glucose and, subsequently, increasing the metabolic activity in these regions. In particular, the brain regions most responsible for appetite, such as the hypothalamus, readily respond to insulin. This reaction to insulin results in a decrease in appetite and a sense of satiety. In contrast, those with insulin resistance have been shown to lack this increase in metabolic activity in these important brain regions following a significant rise in insulin levels. We at the Hunger Free Forever program now know that the brain becomes insulin resistant along with the rest of the body, and that this insulin resistance plays an important role in the loss of after-meal satiety that accompanies weight gain. Think of the appetite control center having an "off" button for appetite that will only respond to insulin. With insulin resistance, the appetite never really gets shut down.
Find out more about this book:Hunger Free Forever: The New Science of Appetite Control