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The examination protocol and data collection methods are fully documented in the NHANES dietary interviewer procedures manuals ( In-person interview  and  phone follow-up interview ).

The in-person interview was conducted in a private room in the NHANES MEC. A set of measuring guides (various glasses, bowls, mugs, bottles, household spoons, measuring cups and spoons, a ruler, thickness sticks, bean bags, and circles) was available in the MEC dietary interview room for the participant to use for reporting amounts of foods ( NHANES Measuring Guides for the Dietary Recall Interview ). Upon completion of the in-person interview, participants were given measuring cups, spoons, a ruler, and a food model booklet, which contained two-dimensional drawings of the various measuring guides available in the MEC, to use for reporting food amounts during the telephone interview. Telephone dietary interviews were collected 3 to 10 days following the MEC dietary interview and were generally scheduled on a different day of the week as the MEC interview. Only a small number of participants (n=120) were interviewed on the same day of the week for both day 1 and day 2 interviews due to their scheduling availability. Any participant who did not have a telephone was given a toll-free number to call so that the recall could be conducted.

What We Eat in America data were collected using USDA's dietary data collection instrument, the  Automated Multiple Pass Method (AMPM) ( http://www.ars.usda.gov/nea/bhnrc/fsrg ). The AMPM was designed to provide an efficient and accurate means of collecting intakes for large-scale national surveys. The AMPM is a fully computerized recall method that uses a 5-step interview outlined below:

1. Quick List - Participant recalls all foods and beverages consumed the day before the interview (midnight to midnight).

2. Forgotten Foods - Participant is asked about consumption of foods commonly forgotten during the Quick List step.

3. Time and Occasion - Time and eating occasion are collected for each food.

4. Detail Cycle - For each food, a detailed description, amount eaten, and additions to the food are collected. Eating occasions and times between eating occasions are reviewed to elicit forgotten foods.

5. Final Probe - Additional foods not remembered earlier are collected.