Time trends and maps

Mean daily intake and 95 % CI were plotted by week of survey completion to explore seasonal variation in dietary intake. Although the data collected refer to the past month, we did not apply a lag period or adjust the date in any way. Broader temporal changes in reported dietary habits over time are visualised with loess curves.

Participants self-reported their current zip code, which we subsequently mapped to states, to characterise the geographic distribution of average intake of food groups, select food items and average BMI across the US Regional average intake was estimated for the South (Delaware, District of Columbia, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, West Virginia, Alabama, Kentucky, Mississippi, Tennessee, Arkansas, Louisiana, Oklahoma and Texas), West (Arizona, Colorado, Idaho, New Mexico, Montana, Utah, Nevada, Wyoming, Alaska, California, Hawaii, Washington and Oregon), Northeast (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont, New Jersey, New York and Pennsylvania) and the Midwest (Indiana, Illinois, Michigan, Ohio, Wisconsin, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota and South Dakota).

For this analysis, the foods selected for seasonality were those with the most pronounced seasonal trends: chocolate, fruit, ice cream and salad. Those selected for mapping showed the most pronounced geographic patterns: fruit, vegetables, whole grains, red meat, processed meat, dairy and pizza.