Glycemic Index & Glycemic Load
A recent trend in dieting is the low glycemic index (GI) diet. The glycemic index is a measure of how quickly a particular carbohydrate is used by the body. The Glycemic Index classifies carbohydrates on a scale to indicate which ones are better to consume if you are trying to lose weight. It's not low carbohydrate; it's more selective carbohydrate.
High or low glycemic index?
Begun as a diet to help people control their diabetes, the general rule of the Glycemix Index diet is: the higher the glycemic index, the faster a food is metabolized by the body. If a food is digested and broken down by the body quickly, your blood glucose (commonly referred to as blood sugar) levels rises rapidly, leading to a quick insulin response, making you feel tired and hungry sooner. Foods with low Glycemic Index are metabolized slower, meaning they sit in your digestive track longer and are gradually absorbed by the body. This leads to a more gradual blood glucose increase, making you feel full longer.
While a few studies have shown that following a low Glycemic Index diet will keep you feeling fuller longer, helping you lose weight, there is no conclusive understanding of how this diet works. Keeping track of the Glycemic Index of foods can get tricky, but this early evidence suggests that it may prove to be a useful tool for dietary planning.
Some factors that affect Glycemic Index (GI)
- Processing - puffed cereals have a much higher GI than the grain they came from.
- Ripeness of fruit - unripe bananas can have a GI of 43, where overripe ones have been clocked at 74.
- Protein content - soy beans have a lower GI than other beans.
- Fat content - peanuts have a very low GI.
- Fiber -orange juice has a higher GI than oranges.
- How small the particles are - whole grains have a relatively low GI, but grinding them into flour shoots up the GI.
Glycemic Index assigns a value to a food based on the average body's metabolism of a simple carbohydrate: usually table sugar or white bread, assigned a value of 100. All other foods are then ranked according to how 50 grams of it, as compared to how 50 grams of sugar or white bread, affects one's blood glucose levels after a period of time. A value below 55 would be considered a low Glycemic Index; a value from 56 to 69 would be a moderate range; anything above 70 is considered to have a high glycemic index. While such values provide a handy guide, they have not been standardized, so two different charts may show a different Glycemic Index value for the same food.
Related to Glycemic Index, glycemic load is a measure that not only takes into account the glycemic index of a food, but also how much of it is there. Since, no matter what, you still have to watch your portion size of any kind of food, glycemic load may be a better dietary tool than Glycemic Index alone. For example, glycemic load can be assigned to an entire meal or to the food eaten over an entire day. "The thinking is, if you have a high glycemic index food, but you have a smaller amount of it, it may have pretty much the same effect of having a low glycemic index food but a larger quantity of it," Grotto said. "So that gets back to looking at portion size."