The following is a mini crash course in how insulin works in the body:
All dietary carbohydrates are broken down into the monomer glucose in the small intestine, which then is absorbed into the bloodstream. Once in the blood, glucose signals the pancreas to secrete insulin. Insulin will then bind to the insulin receptor (IR), where it triggers a series of reactions that ultimately
leads to uptake of glucose and amino acids into the cell, glycogen synthesis, increased muscle protein synthesis, and glucose disposal (glycolysis), usually through the insulin receptor substrate/phosphoinositide 3-kinase (IRS/PI3K) pathway. GLUT4, a transporter needed to allow glucose to enter the cell, is translocated to the cell membrane via activation of the IR, and IRS pathway. Different pathways lead to different actions elicited by insulin, and herein lies how one can maximize the use of endogenous insulin to increase lean body mass or lose body fat.