I once met a man with burnt eyelashes, eyebrows and a shocked look on his otherwise pleasant demeanor. "Flames come out my VCR" he informed me. After thoroughly caring for him and exploring the possibility of airway edema, I further questioned him. "So, unprovoked, flames came shooting at you out of your VCR? Can you elaborate on this, sir?" I was quite skeptical in the matter. The only medical history that he gave me was "accident prone". He went on to say that he had been cleaning his VCR with compressed air. He was attempting to look inside and since he didn't have a flashlight handy, "Boom!", the match gave him a very short and powerful view.
Since I am on a sugar fast, and my brain may be functioning slightly below par, allow me some grace to expound. I will now explain why this story is pertinent. If your body was a furnace, wood would be it's medium of energy for producing heat. Paper, gasoline, compressed air, birch bark and host of other highly flammable materials would provide "a fast burn". Logs, however, especially good hardwood would cause a nice slow burn lasting many hours. The bi product of a good burning wood is clean. The bi product of gasoline, some oil rags, and possibly a can of compressed air would be more flammable and explosive in nature. It would also leave a stink in the air. If you put paper and gas in your wood stove every hour, you would constantly be restarting the stove. If you eat sugar cereal for breakfast, frozen pizza for lunch and McDonald's for dinner, you are doing a similar job on your body. It suffers ups and downs all day long. It gets a "fast burn" and has little sustainable. It is also full of hazardous bi products. This is my very limited explanation of the Glycemic Index. If you eat fruits, vegetables, whole grains, meats and dairy products in proper balance, you will have a sustainable burn. This burn is appropriate to health, weight management and over all good mental functions.
Here are some links on the Glycemic Index.
Another Good Reference to learn from is "Feel Great Look Great" by Joyce Meyer.