Glycemic Index (GI) Calculator
Enter the incremental area under the curve (iAUC) values to calculate the Glycemic Index.
Understanding the Glycemic Index (GI)
The Glycemic Index (GI) is a ranking system for carbohydrate-containing foods based on how quickly they affect your blood sugar (glucose) levels after eating. Foods are ranked on a scale of 0 to 100, with pure glucose serving as the reference food with a GI of 100.
How is GI Calculated?
The GI of a food is determined by feeding a group of people a specific amount (usually 50 grams of available carbohydrate) of the test food and then measuring their blood glucose response over a two-hour period. This response is plotted on a graph, and the "incremental area under the curve" (iAUC) is calculated. The same process is done with a reference food, typically 50 grams of pure glucose. The GI is then calculated using the following formula:
GI = (iAUC of Test Food / iAUC of Reference Food) × 100
The iAUC represents the total rise in blood glucose above the baseline level over the two-hour period. Our calculator uses these iAUC values to determine the GI.
Why is GI Important?
- Blood Sugar Control: Foods with a high GI cause a rapid and significant rise in blood sugar, followed by a quick drop. Low GI foods, on the other hand, lead to a slower, more gradual, and sustained rise in blood sugar. This is particularly important for individuals with diabetes or those at risk of developing it.
- Energy Levels: Stable blood sugar levels from low GI foods can help maintain consistent energy levels, preventing the "sugar crash" often associated with high GI foods.
- Weight Management: Some research suggests that a diet rich in low GI foods may aid in weight management by promoting satiety and reducing overall calorie intake.
- Heart Health: A diet focusing on low GI foods may contribute to better cardiovascular health by improving cholesterol levels and reducing inflammation.
Interpreting GI Values:
- Low GI Foods: 55 or less (e.g., most fruits and vegetables, whole grains, legumes)
- Medium GI Foods: 56-69 (e.g., whole wheat bread, brown rice, sweet potatoes)
- High GI Foods: 70 or more (e.g., white bread, white rice, sugary drinks, many processed snacks)
Limitations of the GI:
While a useful tool, the GI has limitations. It doesn't account for portion size (for that, you'd look at Glycemic Load), how foods are combined in a meal, or individual variations in blood sugar response. Cooking methods and ripeness can also affect a food's GI.
How to Use This Calculator:
To use this calculator, you'll need the incremental area under the curve (iAUC) for the specific test food you're interested in, and the iAUC for the reference food (glucose). These values are typically derived from scientific studies. Input these values into the respective fields, click "Calculate GI," and the calculator will provide the Glycemic Index and its category.
Examples:
Example 1: High GI Food (e.g., White Bread)
- Incremental AUC for Test Food: 800 mmol·min/L
- Incremental AUC for Reference Food (Glucose): 1100 mmol·min/L
- Calculation: (800 / 1100) * 100 = 72.73
- Result: GI = 72.73 (High GI)
Example 2: Low GI Food (e.g., Lentils)
- Incremental AUC for Test Food: 400 mmol·min/L
- Incremental AUC for Reference Food (Glucose): 1100 mmol·min/L
- Calculation: (400 / 1100) * 100 = 36.36
- Result: GI = 36.36 (Low GI)