Data Collection
Dietary intake was measured by two 24-hour diet recalls collected within a 7-day period at each timepoint to account for variation in intake. Dietary output was averaged across the two surveys as previously validated.15 Dietary recalls were administered in either English or Spanish using the Automated Self-Administered 24-hour (ASA24) Dietary Assessment Tool, version 2016, developed by the National Cancer Institute (Bethesda, MD).16 The ASA24 system allowed the participant or their parent to self-administer 24-hour diet recalls using a web-based platform. ASA24 utilizes the United States Department of Agriculture’s Food and Nutrient Database for Dietary Studies (FNDDS) food codes and nutrient values. The method previously described by Lin et al17 was used to assign GI values. Briefly, utilizing the international tables of glycemic index and load, 2008,18 we searched the I-tables 2008 A1, and secondarily, I-tables 2008 A2, for identical or closely matched foods based on their nutritional profiles and preparation methods. If no similar food existed, we calculated GI values by summing the weighted GI value of the component foods. Recipes for combination foods were pulled from FNDDS ingredients lists.19
Anthropometric measures including height and weight were obtained during routine clinic visits. Body mass index (BMI) values were calculated from weight and height (in kg/m2), and BMI percentile and z -scores were calculated according to the 2000 Centers for Disease Control and Prevention reference norms.20Children and adolescents <20 years old were classified as underweight, normal weight, overweight, or obese based on BMI-for-age percentile values <5th, 5-84th, 85-94th, and ≥95th percentile, respectively. Participants >20 years were classified utilizing adult classifications and then converted to z-scores.
A one-time Ease of Study Survey was collected following the completion of the nutrition intervention. The six-question survey was constructed using the five-point Likert scale and queried participants about their experience with the dietary intervention.21 Parent surveys were completed if the participant was <18 years old and patient surveys were completed if the participant was ≥18 years old.