Carbohydrates raise insulin. The ones you want to eat after a workout are high gi (Glycemic Index). White bread, white rice, dextrose and many others.
The Glycemic Index
Blood sugar levels cannot go too high or too low or you will have problems. When blood sugar gets too high insulin is secreted to rush the sugar to the tissue and fill up glycogen stores.
When blood sugar reaches approx. 70mg/dl glucagon is secreted and raises it.
The reason bb's increase want increased insulin post-workout is to rush nutrients to the tissues and refill glycogen stores.