To Your Health September, 2007 (Vol. 01, Issue 09)

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In general, this is the normal, healthy picture of the blood glucose response. The body breaks down carbohydrate slowly, insulin is released slowly, and the liver delivers sustained energy for your daily activities. It also means you shouldn't get hungry too soon after eating.

However, consider what happens if you consume too much carbohydrate, especially carbohydrate with a high GI value. The body breaks the carbohydrate down rapidly, flooding the bloodstream with glucose, which triggers a rush of insulin - too much insulin. The insulin disperses not just the glucose from the food you've just eaten, but much more, which causes blood sugar to drop lower than it should. As a result, those hunger pangs arrive sooner than they should. Not to mention that if you consume too much carbohydrate (excess energy), the body could store it as fat.

A healthy body maintains a blood glucose level somewhere in the range of 60-120 mg/dl at all times. Of course, levels are generally higher immediately after eating, and lower first thing in the morning.

GI Values of Common Foods

• Low-GI foods (55 or less). Examples: most fruits and vegetables (except root vegetables), oats, buckwheat, whole barley.
• Medium-GI foods (56-69). Examples: candy, croissants, brown rice.
• High-GI foods (70 or higher). Examples: corn flakes, white bread, white rice.

It's important to note that the impact a food has on blood sugar may depend on not just the food, but also factors such as ripeness, cooking time, time of day consumed, blood insulin levels and recent physical activity. Take the potato as an example. In a recent study (Journal of the American Dietetic Association, 2005), researchers tested seven different potato-based meals, each providing 50 grams of available carbohydrate. GI values differed markedly based on the type of potato and method of preparation:

• Russet potatoes cooked in a microwave: GI of 76.
• Instant mashed potatoes: GI of 87.7.
• White potatoes, cubed and oven roasted: GI of 73.
• White potatoes cooked in a microwave: GI of 72.
• Red potatoes, cubed and boiled: GI of 89.
• Red potatoes, cubed, boiled, refrigerated 18 or more hours, and then eaten cold: GI of 56.
• Frozen French fries baked in a conventional oven: GI of 63.