Sunday, October 26, 2008

Glycemic index

Bagels and cornflakes and jelly beans, oh my. These--plus baked potatoes--are the worst of the worst of food choices for those of us who do not want to develop diabetes. These foods not only have a high glycemic index but also a high glycemic load. So flakes in the a.m. may leave you flaky and foggy-brained long before lunch.

All carbohydrates are not created equally in that some raise your blood sugar more rapidly than others. The glycemic index (GI) is calculated by measuring the change in blood glucose level that occurs when a person who has been fasting consumes that food. The elevation is then compared to the blood glucose response associated with a standard highly refined, high-carb food such as white sugar (which has a GI of 100).

The higher the GI, the more the food acts in the body like pure sugar, stressing those balancing mechanisms charged with keeping our blood sugar in an ideal operating range. Cornflakes (GI=92) send blood sugar soaring, causing the pancreas to respond with the release of lots of insulin which then efficiently sweeps the carbs into the cells. This causes blood sugar to plummet, leaving Kelloggs consumers with a mid-morning blood sugar too low to sustain brain functioning. While a trip to the office jelly bean (GI=78) jar may restore the blood sugar briefly, this quick fix just perpetuates the vicious cycle.

But nothing is really all that simple. Milk (GI=27) on the cornflakes changes the cereal's effects in unpredictable ways. And some foods with high GIs may have low glycemic loads (GL) which measures the actual blood sugar response to typical servings of foods. So a low GL (considered to be less than 10) on a high GI food choice indicates that you'd have to eat a ridiculous quantity to raise your sugar in ways predicted by its GI. For instance, pineapple has a moderatly high GI of 66 but a low GL of 7. You would have to consume 1 ¾ pounds in a sitting to raise your blood sugar in the same way that a handful of raisins (GI 64, GL 28) would.

Is your head swimming as if you just ate a baked potato (GI 85, GL 26) without sour cream, butter, and a steak (GI 0, GL 0) on the side? Experts agree that this approach may be too complex for many of us, encouraging us instead to eat foods that are not highly processed--which generally increases GI--and a diet that includes a wide variety of fruits, vegetables, and low-fat dairy products.

1 comment:

Cilicious said...

Frankly, I really don't understand all the technical stuff you just described, but I really do understand my sensitivity in regard to blood sugar. An example is breakfast. I always eat it, and 9 times out of 10 it's plain yogurt, fruit, and Kashi cereal. But on the rare occasion that we have pancakes or even just bacon and eggs, I always have a sugar crash around 11am.