Understanding the Glycemic Index
The glycemic index (GI) ranks the effect that foods high in carbohydrates have on blood glucose levels; it measures how much the blood glucose level rises within two to three hours after eating. When eating foods with a high GI value, the blood glucose level will rise more rapidly than that of a low GI value. With the GI, it is not necessarily how many carbohydrates you ingest, but more so the quality of them that are being ingested. The GI is measured by taking the difference of glucose levels after the food has been eaten, dividing by the corresponding area after the control food has been eaten, and multiplying by 100 to obtain a percentage between 1 and 100.
In the weight control aspect, foods with a low GI value tend to provide a feeling of being full for longer, therefore a diet rich in foods with low GI rankings will result in less food being eaten and weight being reduced. Consumption of low GI diets have also been linked to a higher HDL-cholesterol level, the healthy cholesterol, and large studies have showed a decreased risk of developing diabetes and cardiovascular diseases. Positive associations have been shown between dietary GI and the risks of breast and colon cancers. In addition to disease prevention, there are other benefits of consuming a diet with foods low in GI value; one benefit is maintaining a consistent level of energy throughout each day. Foods with a high GI value release glucose into the blood stream quicker and cause the body to overwork itself; with lower GI valued foods, the glucose slowly trickles into the blood stream causing the body to work at a steady pace.
A simple way to switch to a low GI diet is to switch the high GI foods for the low ones. For instance, if you eat white bread, switch to whole grain wheat bread and reduce the amount of potatoes you ingest. One criticism of the GI is the fact that the scale was based around a standard amount of carbohydrates (50 grams) per each food, it does not take the serving size into account, so people do not know the information for the amount of food they are actually eating. Because of this, the glycemic load (GL) was developed. The GL is calculated by taking the GI of a food and multiplying that number by the amount of carbohydrates (in grams) and dividing that number by 100. The difference between the GI and the GL is that the GI only calculates the quality of the carbohydrates in food, whereas the GL takes both the quantity and quality into consideration making the GL more accurate.
Paying attention to the GI and GL of the foods you eat and implementing low GI foods into your diet will be beneficial to your health. In addition to treating and preventing certain diseases, your energy level will be better, and because of the feeling of being full longer, the GI and GL works extremely well for weight control.
For more information on the glycemic index and glycemic load, refer to these resources:
- Glycemic Index and Glycemic Load Chart – a great resource that lists foods and their GI and GL values.
- Glycemic Index and Diabetes – information from the American Diabetes Association on the glycemic index.
- WebMD – more information on the glycemic index.
- Mayoclinic – information on the glycemic index in relation to diabetes.
- Low GI Diets – information on various foods and recipes with a low GI.
- Glycemic Edge – a website dedicated to providing support to those on a GI diet.
- Glycemic Index – additional information on both GI and GL.
- GI Overview – overview of implications in health and disease.
- Glycemic Index and Glycemic Load – Oregon State University information center.
- GI Study – a study on the Blood Glucose Responses to Meals of Varying GI in Youths with Type 1 & 2 Diabetes.
- GI Study 2 – a study on low glycemic index diets versus high fiber cereal in Type 2 diabetes.
- Coronary Heart Disease – a study on the effects of dietary GL and carbohydrate intake on women with coronary heart disease.
- Pregnant Overweight Women – a study on the low GI diet during pregnancy in overweight women.
- Science Daily – a site with various articles on the glycemic index.