The Glycemic Index (GI) is a numerical scale designed to assess postprandial glucose level after digesting a food. Developed by Dr. David J. Jenkins in 1981, it ranks all types of foods on a scale ranging from 0 to 100 based on their respective carbohydrate properties that effect change in user’s blood sugar level. When we ingest food, the carbohydrates it contains are converted to glucose, which is a key ingredient in manufacturing ATP molecules. ATP is the primary source of energy that empowers the body to function and carry on physical activities. Foods with higher glucose content catapult blood sugar level beyond the normal range, an indication of potential onset or aggravation of medical conditions.
The GI measures carbohydrate quality – how quickly a carbohydrate releases glucose to blood – in the food to suggest the total blood sugar increase. With each food assigned a value on the scale, where 100, the highest, symbolizes “an equivalent amount of pure glucose.” Foods with less than 55 GI score ranks for low while those scaled above 55 but less than 70 ranks are considered to be moderate category. A GI score exceeding 70 makes a food high in carb quality.
Glycemic Index and Glycemic Load
GI index assists in measuring glycemic load, which points to the amount of carbohydrates in a food per serving. While focusing only on the postprandial impact, the GI index fails to note how carbohydrate rich a food is and the contribution of a specific serving quantity to blood sugar increase. Glycemic load, calculated based on GI number of a food and carb content per gram, addresses both these problems and ensures a more scientific measurement of blood sugar rise following one serving or an entire day’s intake.
The glycemic load above 20 makes a food rich in carbohydrates. A below 10 score is the one with the lowest possible carbohydrates.
Example: Watermelon scores high (72) on a GI scale, but it has a low carbohydrate content (5%). The glycemic load per 100gm of watermelon is just 3.6 (5 x 72/100). An apple has a GI score of 40 and carb content of about 15 gm per 100 gm. So eating a 100 gm apple provides us a glycemic load of 6 (15 x 40/100). This demonstrates an apple with a low GI score releases more glucose into our blood stream than a watermelon, when served in equal amounts. Similarly, foods such as fructose, despite having low GI score, have the potential to cause high glycemic load when ingested in large quantities.
Importance of Glycemic Index
GI classification offers an advantage in fighting chronic diseases. It has become a tool to diagnose over consumption habits, obesity, and insulin resistance and plan prevention and treatment strategies. Low GI diets are prescribed to treat a wide variety of patients sensitive to excessive and rapid glycemic response.
GI scale helps prevent or control risks associated with diet. Foods with low GI score are considered beneficial for patients suffering from depression, type 2 diabetes, cancer, high cholesterol, kidney disorder, and cardiovascular issues.
Knowing GI scores of food assists in planning our health and fitness program according to age and physical condition. While athletes identify and intake carbohydrate-rich food, those with metabolic syndrome can avoid such types of diet. We also streamline our food habits by becoming selective and more attentive to the carb content in the diet.
High carbohydrate intake has its repercussions in the form of uterine fibroids, neural tube problems, diabetes, kidney ailments, or heart disorders. Awareness of GI score ensures we plan our diet in a form most suitable to avoid or limit such impacts.
GI calculates the exact impact on blood sugar level and ranks a food accordingly. People suffering from diabetes, hyperglycemia, or weight gain need restrained intake of sugars and starches. They found GI physiological assessment a perfect help to avoid high-carb diet and identify a good diet that can boost their fight against disorders.
GI calculation is the best to keep blood sugar level and insulin secretion constant through a balanced diet. If unaware of it, we are prone to eat food with high-glucose to subdue hunger and overcome exhaustion with fast glycemic response. The extra glucose that remains unused coverts into fat and impacts our body shape and fitness levels.