The glycemic index is based on a glucose response to a single food ingested by itself. It does not account for the fact that most foods are eaten in combination with other foods. When eaten in combintion the glycemic index for a given food is of little consequence because of the modifying effects of the other foods. The ADA’s food guide pyramid is, in my opinion, a great fundamental guideline for daily food intake. It’s not magic, it’s just eating sensibly most of the time.