WHAT IS THE GLYCEMIC INDEX & GLYCEMIC LOAD?
The Glycemic Index (GI) is a rating system developed to measure food’s affects on blood sugar levels. Glucose was set at 100 and all other foods were measured accordingly. The higher the glycemic index, the more pronounced an affect a food will have on your blood sugar, and the more stressful to your insulin system. Remember these rules about food and its effects on insulin:
- Carbohydrates - starches and sugars - have the greatest effect. This is especially true if they have little fat or fiber with them.
- Fat has a glycemic effect of zero. Taken with carbohydrates, fat actually blunts the glycemic index. So while a plain baked potato has a high glycemic index, a potato with butter would have a lower one.
- Protein usually has a glycemic effect, but remember that because protein can be readily turned into blood sugar in the liver (via gluconeogienesis), it can raise insulin and blood sugar levels moderately, but usually in a healthy, even way.
Low glycemic index carbohydrates are desirable for weight loss, diabetic control and for keeping HDL cholesterol high. Recent research suggests that it is the high glycemic index carbohydrates that are the ones that lower HDL cholesterol (this would be the bad effect).
Remember that meals are composed of many foods, and it is hard to know what the overall glycemic effect of a given meal will be. But using foods that are lower in the glycemic index will benefit diabetics, those who want to lose weight, as well as those who want to raise their HDL cholesterol.
The glycemic index remains controversial. The important thing to remember is this is just one tool for understanding nutrition and not the end all. For example, fructose is low on the GI scale yet we know it is the most atherogenic of all sugars and can also lead to insulin resistance. Milk also has a low GI but can lead to insulin resistance. Not all foods, especially bakery items and milk products, have a GI index that correlates with the rise in insulin (known as the Insulin Index). Overall, the more refined, lower fiber and processed foods generally tend to be higher on the scale. One clear message from the glycemic index is EAT REAL FOOD.
What is the significance of Glycemic Index?
- A smaller rise in blood sugar and can help control established diabetes.
- Can help people lose weight and lower blood lipids.
- Can improve the body's sensitivity to insulin
- High GI foods can help re-fuel carbohydrate stores after exercise
In short, the goal should be to build a good plan including the low GI foods. This way, hunger is minimized, and there is less tendency to "cheat" or overeat. Consequently, you can continue to lose body fat or maintain your weight - once the excess pounds have been lost.
Even for those whose main objective is not fat loss, foods that are low on the glycemic index will help alleviate mood swings and regulate energy levels.
- Foods that stimulate insulin surges can cause people to eat 60 - 70% more calories at the following meal
- People who consume foods relatively high in glucose (such as white bread, most commercial whole wheat bread, and raisins) eat an average of 200 calories more at the next meal than those who eat fructose (a sugar found in fruits)
Low GI foods can be mixed with modest quantities of high glycemic foods without losing their hunger reducing effect. A low glycemic food plan can be beneficial to:
- Persons with insulin resistance or Syndrome X
High glycemic foods:
- Elevate insulin and blood glucose
- Stimulate fat-storage
- Exacerbate hyperactivity
- Reduce sports performance.
THE GLYCEMIC INDEX and THE GLYCEMIC LOAD
The GI tells us how a particular carbohydrate affects your body’s blood sugar when 50 grams of it is consumed all alone. Generally, the lower the fiber content and the more refined a food is, the higher glycemic index, i.e. white bread has a higher GI than whole grain bread (unless the whole grain bread is finely ground, which breaks down its fiber).
The best way to look at how carbohydrates affect blood sugar is the Glycemic Load (GL). Recent research reveals that is the cumulative effect of GL throughout the day that impacts health the most, not the GI of a single meal or snack.
GL (Glycemic Load) is the GI multiplied by the amount of carbohydrates actually being consumed. For example, a carrot has a GI of 92 and 4 grams of carbohydrates so its GL is (.92 X 4) = 3.68. A mashed potato has a GI of 70 and 37 grams of carbohydrates, so its GL is (.70 X 37) = 25.9. As with the GI, you are better off striving for lower GL value. This is useful when you are eating a higher GI food so that you understand the importance of consuming it in moderation.