The Glycemic Index (GI for short)
Glycemic Index or GI for short is a numerical ranking system used in measuring the comparative degree of absorption and digestion of carbohydrates and their effect on blood glucose. After consumption, a food with a low GI causes a weaker, sustained rise in blood glucose. Foods with a high GI produce a greater temporary spike in blood glucose.
A study in 1981 from the University of Toronto suggested that the GI of foods be used to classify carbohydrates instead of the traditional simple and complex carbohydrate system for the improvement of glucose control among diabetics. GI scores are classified as low (below 55), medium (56-69), or high (greater than 70).
Several factors including the chemical and physical structure of the carb; how refined the carb is; how the carb is cooked; and the presence of other substances may influence the GI value of a food
Differences or Similarities Between the Low Carbohydrate Diet and the Low GI Diet
The premise behind low carbohydrate (carb for short) diets is that all through the day blood sugar, and therefore, insulin levels, are so low that the body is forced to use fat as its main source of fuel. This is similar to what occurs with low GI diet plans. However, the difference lies in low GI diets not restricting carbohydrate intake. Low GI diets are just very discriminating of the carbs picked for consumption.
What is a Glycemic Load?
Glycemic load (GL) fuses both the quality and quantity of a carb into one sum total. The formula is GL = (GI x the quantity of carbs) divided by 100. For example, the glycemic load of a pear with a GI of 25 and 21 grams of carbohydrate is GL = 25 x 21g divided by 100 = 5. The GL of a 2.4 ounce French fries with a GI of 54 and 21 g of carbs is GL = 54 x 21g divided by 100 = 11. In these examples, the fries will have twice the glycemic effect of pear. The GL is the quantity of carbs in a food adjusted for its metabolic power.
Five Glycemic Index Myths
Myth 1 — Potatoes and other white carbs should be avoided because they contain high GI values.
Color of food does not fundamentally determine a high GI. As referred to above, preparation method, quantity of processing and meal composition influence GI, not food color. For instance, the white bread consumed with 35 grams of olive oil has less GI (20) than white bread consumed with 35 grams butter (78). In this example, eating pasta or white bread in combination with fat and protein at mealtime changes their overall GI values.
Myth 2 — The GI is the foremost way to establish the quantity of carbs and sugar in certain foods.
GI declares nothing on carb content. It simply describes the rate glucose is released in the bloodstream. Look at the GL examples above. Both pear and fries have equal number of grams of carb but the fries have a higher GL value. On the other hand, one could consume two unlike foods with a comparable GI. The blood glucose response will still be larger for the food eaten in higher quantity.
Myth 3 — All simple sugar is high in GI.
The GI for most raw fruit is between 30-50 even though they contain the simple sugar fructose (GI 21). Most fruit have a slower rate of absorption and digestion than glucose (GI 93) another simple sugar.
Myth 4 — The GI can be used to determine healthy vs. unhealthy foods.
The GI does not point to whether a food is healthy or not. For example, whole milk has a GI of 27 whereas skim milk has a GI of 32. In this example, lower GI doesn’t constantly mean a healthier product because whole milk contains saturated fat making it a less than healthier choice.
Myth 5 — I can eat unlimited low GI food as I want and keep my insulin levels low.
It is still possible to get rising insulin response with low GI consumption. Bear in mind that the glycemic response is an admixture of GI x carb density. Therefore, the greater grams of carbohydrate eaten will still result in greater insulin levels.
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