Have you ever been sitting in school or church and you suddenly feel shaky, and a little agitated? You may even sweat, get tunnel vision and feel like you need to eat something right away. This could result from blood sugar levels being out of their normal range. I have problems with this, which is partly why I am eating the way that I am eating now. The glycemic index (GI) measures how fast a food is likely to raise your blood sugar.
Even without blood sugar issues being familiar with the glycemic index has tons of benefits. Low GI foods are associated with weight control, reduction in heart disease, an ability maintain prolonged exercise, and a reduction of hunger (who doesn't want that?).
As the table above indicates 70 or above is high and 55 or under is low.
Link to glycemic index database