Adventures in diet records: Superbowl Sunday 2009 4 March 2009 10:29 am
Posted by Tracy in : eating,food snobbery,geekery,nutrition,school , trackbackYes, that’s right, kids, I kept a 24-hour diet record on Superbowl Sunday. The assignment for my nutrition class was to record everything I ate in a 24-hour period, preferably on a relatively typical day. Problem: much of my eating during the week of the assignment was designed to show our guests the awesomeness of New York City’s many delicious restaurant options. I do not typically eat most of my meals out, but that week I made many tasty exceptions to that rule. That said, I typically eat a little better than I did on Superbowl Sunday 2009, and looking over the data I took that day makes me more than a little defensive.
The good news? According to Dr. Nestle in class on Monday, one point of the exercise (and filling out the Harvard Food Frequency Questionnaire) was to show the limitations of diet data. Yay! Also, I was especially delighted to learn about a 1984 study that demonstrated the huge variance in day-to-day nutrient intake (Basiotis et al., “Number of Days of Food Intake Records Required to Estimate Individual and Group Nutrient Intakes with Defined Confidence,” The Journal of Nutrition, (1987) 117:1638–1641). Volunteers filled out daily 24-hour-diet records for a whole year, and researchers analyzed them in terms of food energy and 18 nutrients, and calculated the average number of days of data needed to get a good approximation of yearly average consumption of a given nutrient, both for individuals and for groups. Results varied hugely from nutrient to nutrient, and were especially dramatic at the individual level, where it took an average of 31 days of data to reach a reasonable approximation of average food energy intake (calories). For Vitamin A, the researchers calculated it would take 433 days of 24-hour diet record data to approximate average individual consumption! Less data was needed to calculate averages for the group (3 days for calories, 41 for Vitamin A), and the researchers concluded that the larger the group surveyed, the fewer days of data would be needed to get good averages — but still. This stuff is demonstrably HARD. (P.S. Do not get me started on the problems with the food frequency questionnaire.)
Anyway, with all that fancy science as a disclaimer (and deterrent for anybody who didn’t want to read through it), I feel better about posting this link to the Google spreadsheet of my diet record data. I’m still expanding on it with information from the big USDA nutrient analysis tables, but long story short is: I ate kind of a lot of junky food on Superbowl Sunday. I really shouldn’t be surprised.
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Ellen
