Wednesday, July 14, 2010

Glycemic Index, Glycemic Load and Glycemic Response

Being aware of the glycemic index (GI) and glycemic load (GL) of certain foods can help you control your glycemic response and body fat. The glycemic index is a numerical index that ranks carbohydrates based on their rate of glycemic response, or their conversion to glucose within the human body. The Index uses a scale of 0 to 100, with higher values given to foods that cause the most rapid rise in blood sugar. Pure glucose is the reference point and has a GI value of 100.

A low-carb diet is not necessary. You are better off eating the right kinds of carbohydrates at the right time. Your body depends on carbohydrates as a primary fuel source (especially during intense workouts). For instance, after a tough workout, a post-workout drink with high glycemic carbs and protein will help your body recover and rebuild your muscles. During the day, low glycemic carbs are more desirable.

The glycemic index is important because your body performs best when your blood sugar is kept relatively constant. When blood sugar drops too low, you become listless or experience increased hunger. If it goes too high, your brain signals your pancreas to secrete more insulin. Although insulin will bring your blood sugar back down, it does so primarily by converting the excess sugar to stored fat.

For non-diabetics, there are times when a rapid increase in blood sugar is desirable. For example, some coaches and trainers recommend high GI foods (like sports drinks) immediately after exercise to help speed recovery.

Another way to control your GI is to also control your glycemic load (GL). Glycemic load can be controlled by the type and amount of carbohydrates you consume. So, GI and GL work together to control your glycemic response.

Listed below is a table showing GI and GL for some common foods. GI's of 55 or below are considered low, and 70 or above are considered high. GL's of 10 or below are considered low and 20 or above are considered high.

Food GI, Serving Size, Carbs, GL

Peanuts 14, 4 oz (113g), 15, 2
Bean sprouts 25, 1 cup (104g), 4, 1
Grapefruit 25, 1/2 large(166g), 11, 3
Pizza 30, 2 slices (260g), 42, 13
Lowfatyogurt 33, 1 cup (245g), 47, 16
Apples 38, 1 medium (138g), 16, 6
Spaghetti 42, 1 cup (140g), 38, 16
Carrots 47, 1 large (72g), 5, 2
Oranges 48, 1 medium (131g), 12, 6
Bananas 52, 1 large (136g), 27, 14
Potato chips 54, 4 oz (114g), 55, 30
Snickers Bar 55, 1 bar (113g), 64, 35
Brown rice 55, 1 cup (195g), 42, 23
Honey 55, 1 tbsp (21g), 17, 9
Oatmeal 58, 1 cup (234g), 21, 12
Ice cream 61, 1 cup (72g), 16, 10
Mac & cheese 64, 1 serving(166g), 47, 30
Raisins 64, 1 small box(43g),32, 20
White rice 64, 1 cup (186g), 52, 33
Sugar 68, 1 tbsp (12g), 12, 8
White bread 70, 1 slice (30g), 14, 10
Watermelon 72, 1 cup (154g), 11, 8
Popcorn 72, 2 cups (16g), 10, 7
Baked potato 85, 1 medium (173g), 33, 28
Glucose 100, (50g), 50, 50

Things to Consider When Using Glycemic Index/Glycemic Load

1. Generally, any food processing such as grinding or cooking will elevate GI values for certain foods.

2. The addition of other foods that contain fiber, protein or fat will generally reduce the GI of the meal.

3. The rate of glycemic response varies from person to person. Also, a person's glycemic response might vary depending on the time of day. And different people have different insulin responses. Lesson? GET TO KNOW YOUR BODY!

4. IF YOU USE GI AND GL VALUES AS THE SOLE FACTOR FOR DETERMINING YOUR DIET, YOU COULD END UP OVERCONSUMING FAT AND TOTAL CALORIES. GI IS ONLY USED TO RATE A FOOD'S CARB CONTENT. IF YOU EAT MORE CALORIES THAN YOU BURN, YOU WILL GAIN WEIGHT NO MATTER WHAT YOU EAT.

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Mark Dilworth, BA, PES
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