The Gylcemic Index, Part 1

Increasing numbers of people have to learn more than they ever wanted to know on the subject because of diabetes (hyper-glycemia) or hypo-glycemia. (Hyper means high and hypo means low.) Diabetes is commonly identified with high blood sugar although a diabetic may go into a coma because of low blood sugar.

Most women, seeking thinness through starvation (“anorexia nervosa”), have also experienced bouts of low blood sugar when they, quite literally, have to sit down and struggle to consume something sweet (candy or fruit juice) to revive them before they fall down. Once consciousness is completely lost, there is no other recourse than an injection or IV glucose solution.

Another at-risk population is the sick child who has no appetite or thirst. Their small size contains limited fluids and supermarket products like Pedialyte can literally save a hospital visit or a life! Most athletes have experienced low blood sugar when they are forced to drop their speed or stop altogether, like Pamela Newby Fraser in the recent Ironman. Cyclists usually term this “Bonking”, or for marathon runners it is “hitting the wall”.

Carbohydrate deficiency hinders performance by depriving the muscles of the primary energy source. Chronic depletion leads to further decrements and possibly prostration. It also impairs thought processes as the brain consumes huge amounts of blood sugar!

Are you piecing it together? Yes, glycemic refers to blood sugar. The Glycemic Index, then, indicates how rapidly and completely a food sugar enters the bloodstream compared with the standard of glucose.

Carbohydrate foods are listed in the accompanying table and it may surprise people that “not all carbohydrates are created equal”! A late night pizza and an early pancake breakfast will not boost your chances for a morning 5K run! A 5K doesn’t consume much energy and these choices are loaded with fats.

There are 3 types of carbohydrates, only two being discussed here: simple and complex. The other, fiber, is mainly indigestible and involved with elimination.

Simple sugars enter the bloodstream quickly, characterizing a high glycemic index. Normally, the high influx of glucose stimulates the pancreas to secrete insulin, which removes excess glucose.

(Diabetics have impaired insulin and must depend on tablets or injections to control their blood sugar.)

Attempts to boost blood sugar levels may also “backfire” in normal individuals because of insulin rebound, i.e. high sugar, evokes an insulin reaction which explains why we often feel sleepy after lunch, especially over the holidays! Instead of being energized, you’re sleepy and feel worse.

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