One of the neatest things about the annual Consumer Expenditure Survey (CEX) is that you can track changes in how Americans spend money over time. Some of those changes can explain a lot about Americans have themselves changed.

Let's start by reviewing how much the average American household spends on food each year in the context of their total expenditures, where the amount spent on Food ranks third highest in all years. The first chart below reveals that the average amount American households spend on food each year has fairly steadily risen from $3,290 in 1984 to $7,923 in 2018. But as you can see in the second chart, the relative amount that Americans spend on food each year has declined as a share of total household expenditures in the 35 years from 1984 through 2018, from 15.0% to 12.9%. [Please click on the charts to access larger versions.]

We've dug deeper into the food category, which the CEX divides into the two subcategories of "Food At Home" and "Food Away From Home". In the next two charts, we visualize both the amount of annual spending on these subcategories and also the share of spending for each with respect to the average household's total food expenditures for each year from 1984 through 2018.

For the "Food At Home" category, the average amount spent each year by an American household has increased from $1,970 in 1984 to $4,464 in 2019. For the "Food Away From Home" category, the spending numbers have changed from $1,320 to $3,459 over the same period. As a share of average total food expenditures, the percentage of food at home with respect to total food expenditures has held relatively stable over all that time, ranging between a low of 56% and a high of 62% from 1984 through 2018, trending toward the low end of that range in recent years.

Fortunately, the CEX breaks the "Food At Home" category down into finer subcategories, which gives us some remarkable insight into how the American diet is actually changing over time. In the following charts, we've visualized the average household expenditures of the major subcategories of "Food At Home" from 1984 through 2018 and also how the share of those subcategories are changing:

The first chart reveals that average household expenditures for all these subcategories has risen from 1984 to 2018, but one has risen considerably faster than all the others: "Miscellaneous Foods". Here's how the CEX describes what's in this subcategory of Food At Home:

Miscellaneous foods includes frozen prepared meals and other foods; canned and packaged soups; potato chips, nuts and other snacks; condiments and seasonings, such as olives, pickles, relishes, sauces and gravies, baking needs and other specified condiments; and other canned and packaged prepared foods, such as salads, desserts, baby foods, and vitamin supplements.

That description of the kinds of foods included in the "Miscellaneous Foods" category stood out to us because it closely resembles what a team of National Institute of Health nutrition researchers categorized as "ultra-processed foods" in a ground-breaking randomized controlled trial experiment they conducted in 2018, the results for which they published earlier this year. They explained the context and significance for that distinction in their paper:

Increased availability and consumption of ultra-processed foods have been associated with rising obesity prevalence, but scientists have not yet demonstrated that ultra-processed food causes obesity or adverse health outcomes. Researchers at the NIH investigated whether people ate more calories when exposed to a diet composed of ultra-processed foods compared with a diet composed of unprocessed foods. Despite the ultra-processed and unprocessed diets being matched for daily presented calories, sugar, fat, fiber, and macronutrients, people consumed more calories when exposed to the ultra-processed diet as compared to the unprocessed diet. Furthermore, people gained weight on the ultra-processed diet and lost weight on the unprocessed diet. Limiting consumption of ultra-processed food may be an effective strategy for obesity prevention and treatment.

To illustrate what the researchers mean by ultra-processed foods, check out the daily menus they developed for comparing the effects of diets based on ultra-processed versus unprocessed foods in their clinical trial, where the "ultra-processed" category aligns with much of what is in the CEX's "Miscellaneous Foods" subcategory.

The NIH researchers also identified an economic contributor to what the CEX confirms in the changing composition of the average American diet over time:

The weekly cost for ingredients to prepare 2,000 kcal/day of ultra-processed meals was estimated to be $106 versus $151 for the unprocessed meals as calculated using the cost of ingredients obtained from a local branch of a large supermarket chain.

Miscellaneous foods have grown from 11% of the average total expenditures for the "Food At Home" category in 1984 to 20% of total expenditures in 2018, where this subcategory including ultra-processed foods now ranks as the second highest within the "Food At Home" category the CEX tracks.

This change coincides with a rising incidence of obesity in the United States over this period, where the U.S. ranks only behind Mexico*, which has also experienced increased rates of obesity since the early 1980s. The combination of studies and consumer trends explains why ultra-processed foods are now being subjected to much greater scrutiny by scientists and U.S. policy makers, although policy makers have recently fixated their attention on using tax policies to reduce sales of sweetened beverages because they provide a simpler path for increasing tax revenues, even if the soda taxes provide few, if any, meaningful health benefits for the populations subject to them.

* Mexico has coincidentally also seen a similar rising trend for ultra-processed food purchases, which researchers report have doubled since 1984.

References

U.S. Bureau of Labor Statistics and U.S. Census Bureau.  Consumer Expenditure Survey.  Multiyear Tables.  [PDF Documents: 1984-1991, 1992-1999, 2000-2005, 2006-2012, 2013-2018]. Reference Directory: https://www.bls.gov/cex/csxmulti.htm. Accessed 10 September 2019. 

Hall, Kevin D. et al. Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake. Cell Metabolism: Clinical and Translational Report. Volume 30, Issue 1, pp 67-77. https://doi.org/10.1016/j.cmet.2019.05.008. 2 July 2019.