All you need to know about glycemic index

The glycemic index provides information on how food affects blood sugar and insulin. The rate of glycemic index is 1-100. Pure glucose has 100. Products with low GI h have less than 55 GI and these types of food do not raise your blood sugar level rapidly. Products with more than 70 are high GI and they can cause a sugar rush and in the long term, many diseases.

The higher the glycemic index, the faster is the absorption of sugar in our blood stream, muscles and liver. We will feel the energy but then in time, our blood sugar will droop and we will feel fatigued, hungry and we can have sugar cravings.

High glycemic index food can cause sugar rushes: dizziness, hot flushes, shaking hands, sweating, problem with concentration, coronary heart disease, diabetes, increased cholesterol and obesity.

As a personal trainer I would recommend maintaining a low glycemic index diet especially for women and people who can have issues with overeating. It will help to uphold stable energy levels and to lose fat.

There is another term we need to know; the Glycemic load which tells us how many carbohydrates food contains.

GI and training:

Before training, I would recommend eating low GI food so we can maintain slow release energy which can last for the entire duration of training. We need carbohydrates to replace glycogen in the liver and muscles. While training more than one hour we can improve our performance with medium and high GI food (after one hour of training it is recommended to take 30-60g carbohydrates). Following training it is recommended to take high GI products.

Two important things you should remember:

  1. Personal blood sugar response means that not every low GI food has the same effect on everyone. Some products with low GI like banana and medium GI grapes can raise your blood sugar level. Try and observe your body reactions.
  2. It is not always that low GI food is a healthy option. For example Cookies ( 55-65) and bread (70), potatoes chips (54) and potatoes baked without fat (80). Sometimes products with saturated fat cause coronary heart disease have lower GI index.
GI and GL for Common Foods by Harvard University
Food GI    Serving Size Net 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
Lowfat yogurt 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
Macaroni and cheese 64   1 serving (166g) 47 30
Raisins 64  1 small box (43g) 32 20
White rice 64   1 cup (186g) 52 33
Sugar (sucrose) 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