This is the second in a series on Low Carb Dietary Recall Research. Glycemic Index is the impact on blood sugar by foods. The Glycemic Load measures the impact of a meal. Daily Glycemic load would cover and total all food during the day.

Standardized software ( The NDSR - Nutrition Data System for Research) is used by nutritionist interviewers to find matches to the foods. After the food matches are made, the glycemic index must be calculated. That's done using other standard databases (the International Table of Glycemic Index and Glycemic Load Values and the University of Sydney online databases).

After these data are found, calculations have to be made. The frequency and amount of foods ingested must then be calculated. Findings were blinded and replicated. Repeat calculations were found to have a high correlation.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1989668/