The COVID-19 pandemic changed far more than where people ate. It also reshaped what they brought home, how much they spent on different types of food and, in some cases, the nutritional character of entire household shopping baskets. A large analysis of purchasing behaviour in the United States now suggests that these changes did not simply disappear when lockdowns ended. Instead, the pandemic appears to have produced a complicated dietary legacy: households initially shifted towards foods that were less processed, but spending on ultraprocessed products later climbed above pre-pandemic levels. The pattern was not uniform across income groups, food categories or methods used to define a healthy diet.
The study, published in Nature Human Behaviour, examined 9,367,550 weekly shopping baskets collected from more than 30,000 US households between 2017 and 2022. This long observation period allowed the researchers to compare purchasing patterns before the pandemic, during the disruption of 2020 and 2021, and in the post-pandemic period. The researchers combined household purchasing data with county-level information on pandemic policies, including restrictions that influenced mobility and retail activity. They also used artificial intelligence-assisted nutrition profiling to classify the foods purchased and assess changes in dietary quality at scale.
The results reveal a striking reversal over time. During the early pandemic and periods of lockdown, households increased the share of spending directed towards less processed foods. Such a shift may reflect the unusual circumstances of that period. With restaurants closed or operating under restrictions, families prepared more meals at home, while disruptions to daily routines may have encouraged purchases of basic ingredients and foods requiring preparation. At the same time, consumers faced uncertainty over supplies, employment and access to shops. The study indicates that the initial movement towards less processed products was not a permanent transformation of the American food basket.
In the period after the acute phase of the pandemic, spending on ultraprocessed foods rose above levels observed before COVID-19. Ultraprocessed foods are industrial formulations typically made using multiple ingredients and additives, and are often designed to be convenient, highly palatable and shelf-stable. They include many packaged snacks, ready-to-eat meals, sweetened products and processed beverages. The findings do not mean that every household adopted the same diet, nor that all processed foods have identical nutritional effects. Rather, they show that the balance of household spending moved in a direction associated with greater reliance on heavily industrially formulated products.
One of the study’s most important findings concerns how diet quality is measured. The shift was especially clear when foods were classified according to the NOVA system, which groups products by their degree of industrial processing. However, the same divergence was less pronounced when researchers used nutrient-based measures, including the Healthy Eating Index and the Food Standards Australia New Zealand nutrient profiling model. These tools assess food quality through characteristics such as nutrients, food components and overall dietary composition rather than processing alone. A product can therefore be highly processed without fitting every definition of nutritional poor quality, while a minimally processed food can still be high in salt, sugar or saturated fat.
This difference between measurement systems is scientifically important because it shows that “healthy” and “processed” are not interchangeable terms. NOVA can capture industrial transformation and the role of convenience foods in modern diets, but it does not directly measure every nutrient or dietary benefit. The Healthy Eating Index is designed to assess alignment with dietary guidance, while the FSANZ model evaluates nutritional attributes used in food profiling. By comparing all three approaches, the researchers found that each describes a different dimension of food purchasing. The study therefore supports using processing-based and nutrient-based measures together instead of treating any single score as a complete description of diet quality.
The pandemic also altered the relationship between food spending and household socioeconomic status. In 2020, the spending gap between socioeconomic groups widened, suggesting that the shock affected purchasing power and food choices unevenly. Yet the researchers report that this difference converged after the pandemic. A different pattern then appeared: a nutrition gap emerged as higher-income households increased spending on less nutritious foods. This result challenges the assumption that greater income automatically produces healthier purchasing. Resources can expand access to fresh foods and health information, but they can also increase the ability to buy convenience products, restaurant-style foods and premium ultraprocessed products.
Some food categories showed effects that persisted beyond the most disruptive months of the pandemic. Prepared foods, frozen foods and carbonated beverages were among the categories associated with lasting changes. Their persistence may reflect habits formed during periods when consumers prioritised convenience, storage life and reduced shopping frequency. Frozen and prepared products can help households manage time and uncertainty, while carbonated beverages are often heavily marketed and widely available. The continued presence of these categories in post-pandemic purchasing suggests that temporary crises can accelerate changes in the food environment that remain embedded after restrictions are lifted.
Because the analysis used purchasing baskets rather than direct records of everything people consumed, it cannot establish precisely what each person ate or prove that the pandemic alone caused every observed change. Food bought in stores may be shared, wasted, consumed outside the home or combined with ingredients purchased elsewhere. Even so, the scale and duration of the dataset provide an unusually broad view of household behaviour. By linking weekly purchases with local policies and applying several nutrition frameworks, the researchers were able to distinguish short-term disruption from longer-term change more effectively than a snapshot survey could.
The findings carry a warning for public-health planning. Food policies designed only for the emergency phase of a crisis may miss the habits that persist after the emergency ends. Support for affordable fresh foods, clear front-of-pack information, healthier prepared and frozen options, and restrictions on the promotion of products with poor nutritional profiles could help make food systems more resilient. Interventions may also need to account for socioeconomic differences without assuming that higher-income households are automatically protected from unhealthy trends. The pandemic did not produce one universal dietary response; it exposed how policy, convenience, income and food formulation interact. Understanding that complexity may be essential for preventing the next crisis from leaving behind another nutrition gap.
Subject of Research: US household food purchasing behaviours, nutrition quality and socioeconomic disparities during and after the COVID-19 pandemic
Article Title: Short- and long-term shifts in food purchasing behaviours and nutrition disparities in the USA during and after the COVID-19 pandemic
Article References:
Hu, G., Lu, W., Soberman, D. et al. Short- and long-term shifts in food purchasing behaviours and nutrition disparities in the USA during and after the COVID-19 pandemic. Nat Hum Behav (2026). https://doi.org/10.1038/s41562-026-02547-9
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41562-026-02547-9
Keywords: COVID-19 pandemic, food purchasing, ultraprocessed foods, nutrition disparities, household diets, socioeconomic inequality, NOVA classification, Healthy Eating Index, food policy, public health
