Inadvertent Intervention: Ultra-Processed Food Consumption and Adiposity Outcomes Among US Adults Before and After the COVID-19 Pandemic

Abstract

Ultra-processed foods (UPFs) have comprised the majority of caloric intake among US adults for more than two decades, continuously increasing as structural food environments have been engineered to make processed options the default. The COVID-19 pandemic disrupted these conditions in unprecedented ways, and the net effect on UPF consumption at the population-level was unresolved. Using nationally representative dietary recall data from 12,498 US adults in two cycles of the National Health and Nutrition Examination Survey (NHANES), this paper estimates changes in UPF consumption across the pre-pandemic (2017–March 2020) and post-pandemic (August 2021–August 2023) periods, examines demographic heterogeneity in those changes, and tests whether the association between UPF consumption and adiposity outcomes differed between periods. UPF consumption decreased significantly from 55.05% to 52.84% of total daily energy intake post-pandemic (p = 0.033), a 2.21 percentage point decline that was demographically uniform across age, sex, race and ethnicity, income, education, and employment status. Higher UPF consumption remained significantly associated with a higher Body Mass Index (BMI), a larger waist circumference (WC), and greater odds of overweight, obesity, and abdominal obesity in fully adjusted models, with no evidence that these associations differed between periods. These findings suggest that the pandemic functioned as an inadvertent structural intervention, producing a moderate but real population-wide improvement in diet quality, which targeted behavioral interventions have consistently failed to achieve. The stability of UPF–adiposity associations across periods indicates that the biological consequences of ultra-processed diets do not diminish when food environments shift. Together, the results support a reorientation of US dietary policy toward a change in the structural food environment to improve public health.