I just found an excellent post and indepth explanation of the Glycemic Index on the Advancing Health Blog. If this story reminds you of you do click on the link at the bottom for more information including a happy ending ...
"I was thin most of my life and then it hit me. I started gaining weight around my middle, my thighs, chest and neck. Even my face became fat! I went to my doctor and asked him what I could do. He said, "Exercise more and eat less." Well, duh! I was expecting something a little more profound than that. I followed his advice and came back in a month. When I got on the scale, I weighed MORE! How could this be, doc? He said that when I increased my exercise, it must have made me hungrier and I must have eaten more. I don't think so. When I was younger, all I had to do was think about losing weight and it would come right off (fast). Why was it so tough now? It's a simple formula, isn't it? Burn more calories than you take in. I had done that all my life and it always worked before. What had changed?
I did not know it but I had put my body on a high-glycemic roller coaster ride. For many years, it was not a problem. My body seemed to handled it just fine with no telling symptoms. Then, all of the sudden, I started putting on 10-15 pounds a year. I was always tired in the afternoon and I found that my memory was not as good as it had been before. The results of the roller coaster had finally caught up with me.
Here's how the glycemic roller coaster works." (Click there for the rest of the story.)