Examining diet trends in the United States

An investigation looks into how the US diet has change since 2003.

The average American diet has changed over the past 30 or so years, with a decrease in home-cooked meals and, in the late 1990s, a proliferation of convenience foods.1 An investigation in JAMA Network Open examines the trends in the nutritional quality of the foods consumed from major food sources in the United States.2

The investigators included respondents from 8 National Health and Nutrition Examination Survey cycles, 2003 to 2018, who had valid dietary memories. The average diet quality of foods, which included meals, snack, and beverages, were characterized by American Heart Association diet score (range, 0-80, with higher scores indicating healthier diets), the Healthy Eating Index 2015 (range, 0-100, with higher scores indicating healthier diets), and their components. Using the American Heart Association diet score, a poor diet was defined as less than 40.0% adherence (score, <32.0); intermediate diet as 40.0% to 79.9% adherence (score, 32.0-63.9); and ideal as 80.0% or greater adherence (score, ≥64.0).

A total of 20,905 children aged 5 to 19 years were included in the study, along with a cohort of 39,757 adults aged 20 years and older. The diet quality of food from grocery stores had a modest increase over the span of time (53.2% to 45.1% with poor diet quality; P = .006 for trend). Restaurant diet quality for children saw smaller changes (84.8% to 79.6% with poor diet quality; P = .003 for trend). However, food quality from other sources worsened overall (children: 40.0% to 51.7% with poor diet quality), but there was some good news as there was a major improvement in diet quality in schools, with poor diet quality decreasing from 55.6% to 24.4% (P < .001 for trend), mostly after 2010, likely at least in part because of the Healthy, Hunger-Free Kids Act of 2010, which was championed by former First Lady Michelle Obama.

The investigators concluded that the most significant positive impact on diet quality came from the foods that were consumed at school, which had little population disparities. They urged for additional improvements in other major food sources and that those improvements should focus on achieving equity.


1. US Department of Agriculture. US Households’ demand for convenience foods. Published July 1, 2016. Accessed April 15, 2021. https://www.ers.usda.gov/webdocs/publications/80654/err-211.pdf?v=0

2. Liu J, Micha R, Li Y, Mozaffarian D. Trends in food sources and diet quality among US children and adults, 2003-2018. JAMA Netw Open. 2021;4(4):e215262. doi:10.1001/jamanetworkopen.2021.5262