10) GLYCEMIC INDEX
a) Introduction
The "glycemic index" is a measure of how fast a mouthful of carbohydrate food will turn into simple sugar and move into the blood stream, ten minutes or four hours, or something in between. In technical terms the glycemic index is a measure of how rapidly 50 grams of carbohydrates in any given food will raise the blood sugar level over a span of two hours. A high glycemic index of 100 indicates very rapid conversion of the carbohydrate into blood sugar and a rapid rise in blood sugar level as a result. A glycemic index of 50 indicates in a rough way that 50% of the carbohydrates go into the blood stream in less than two hours and that 50% of the carbohydrates go into the blood stream in over two hours. A surprisingly little amount of a high glycemic index food can really raise the blood sugar levels to high levels very rapidly, but it doesn't have to do it. It is a highly individualized reaction. The glycemic index is the subject of much debate among the experts.
Part of the problem with the use of the "glycemic index" is the definitions of "low", "moderate" and "high" glycemic index. Each study uses a different definition. Most of the studies defined "low" as below 70 and "moderate" between 70 and 80. That means that on a "low" glycemic index diet only 30% of the carbohydrate intake is delayed. In our opinion this isn't anywhere near low enough for the purposes of a person with diabetes. Anyone with diabetes should be limiting themselves to "very low" glycemic indexes, in the range of 50 and below. High fiber unprocessed carbohydrates (beans, vegetables, high fiber cereal) and the dairy carbohydrates that are most recommended for people with type two diabetes are all well below 50 on the glycemic index. Doctor Bernstein only wants individuals to eat foods with a glycemic index less than 15!
Another of the problems with the glycemic index is that it is so individualized that it is difficult to generalize from the tables. But just because the glycemic index is at best a very rough indicator of speed of assimilation doesn't mean one should be throwing out the baby with the bath water. If one looks at the foods most diabetics should be eating per most experts, one will find only very low glycemic index foods, typically with a glycemic index below 40 or 50. Using this very low glycemic index rule, the glycemic index does clearly have two effects; it has a small effect (minus 0.5 to 0.7 A1c) on the A1c by affecting the roughly first half hour after eating a food, and it positively affects dieting of some individuals by preventing high/low blood sugar cycling though out the day. I.e. it is helpful but not a panacea.
The glycemic index of a carbohydrate food will be raised the more it is cooked and the more it is chewed. Incorporating fat or fiber into the carbohydrate will reduce the glycemic index. Taking vinegar, lime juice or lemon juice with the carbohydrates will supposedly slow stomach emptying and decrease the glycemic index of any carbohydrate (Although we have difficulty believing that the slight acidity of these foods will not be overwhelmed by the 1.5 ph acidity of the hydrochloric acid in the stomach).
The glycemic index does have an effect on the author's blood sugars. Here are a few results he obtained:
Low Glycemic results
During a day of light, frequent, low glycemic load snacks
8/21 3:00 PM ..................................................................................1312 hours after a low glycemic meal
8/23 9:30 PM (chicken and cheese) ...........................................138
8/24 9:00 PM (1 scoop ice cream!) ............................................131
8/27 10:26 PM (Tilapia, veggies) ................................................131
9/3 9:50 PM (salmon, veggies) .....................................................894 hours after low glycemic load meal
8/21, 9:00 PM ..................................................................................88Test - Ate low glycemic meal at 5:30 pm
8/30 6:30 PM .................................................................................103
8/30 7:33 PM .................................................................................101
8/30 10:00 PM ...............................................................................128Test - Ate large bowl of raspberries and starch-free yogurt at 5:30 pm
8/31 6:30PM ...................................................................................108
8/31 7:30PM ...................................................................................101High Glycemic Results
2 hours after high glycemic meal
8/22, 9:00 PM (2 no-sugar low fat yogurts)............................... ....188
All small yogurts have loads of "modified food starch"
8/25 9:22 PM (large 4 course meal).............................................. 160
A large meal is bad even if made up of low glycemic foods
9/8 7:02 PM (1 ½ hr after 4 all beef franks)................................... 192
Beef Franks are loaded with corn starch fillerTest - Ate large bowel of chili with beans (and sugar in ingredients) at 6:30 pm
8/29 6:30 PM ....................................................................................101
8/29 7:30 PM ....................................................................................172
8/29 9:15 PM ....................................................................................122Test - Ate bag of popcorn at 7:15 PM
9/6 8:30 PM ......................................................................................231
9/6 9:20 .............................................................................................235It has to be emphasized that this is a highly individualized reaction. The glycemic index obviously applies to the author but it might not apply to another person with type 2 diabetes. Or foods which affect the author might not affect others the same way. This is why it is so important to test blood sugar frequently and to keep a diary.
Current Chapter: 10) GLYCEMIC INDEX
a) Introduction
b) Types of Common Carbohydrates
c) Glycemic Index and A1c
d) Glycemic Index and Losing Weight
e) Glycemic Index Controversy
f) Using Bad Statistics to Judge the Glycemic Index
g) The Occasional High Glycemic "Splurge"
h) Glycemic Load
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