New study links higher ultra-processed foods consumption to US diet decline

A recent US study is calling attention to a national diet crisis and outlining a data-driven path forward. Led by experts from leading universities and Nourish Science, the study’s analysis of national nutrition data reveals that more than 86% of Americans fall into the “low” or “very low” diet quality categories, with over half of the US population classified in the lowest tier.

Using data from the National Health and Nutrition Examination Survey (NHANES) and measured against the Healthy Eating Index-2020, the researchers created four novel, evidence-based diet quality categories: high, marginal, low, and very low.

These “cut points” are designed not only to reflect current dietary patterns, but also to serve as a tracking tool for policy makers and health leaders to assess progress in improving national nutrition standards and reduce the percentage of Americans with poor diet quality.

“Despite growing concern about diet-related chronic disease in the US, national monitoring of diet quality by meaningful categories has largely been missing,” says Elise Sheinberg, a doctoral student at the Harvard T.H. Chan School of Public Health and the study’s lead author.

“These new data provide nationally representative evidence for using diet quality categories to set goals for reducing the number of Americans with very low diet quality and reduce chronic disease nationwide.”

Call to strengthen SNAP-Ed

Published as a preprint on medRxiv, the study raises urgent concerns about the health of the American public — and the systems designed to protect it.

The findings underscore that the majority of US citizens consume diets high in ultra-processed foods (UPFs), refined grains, and processed meats — key drivers of poor cardiometabolic outcomes. The data also shows clear disparities. Only 2.4% of adults in households with low or very low food security achieve high diet quality.The research suggests higher US UPF consumption to lower diet quality.

This inequity highlights a pressing call from researchers to embed diet quality as a central objective in the Supplemental Nutrition Assistance Program (SNAP) and maintain funding for SNAP-Ed, the USDA’s leading nutrition education initiative. Currently, SNAP-Ed is the federal government’s primary mechanism to improve diet quality and prevent chronic disease in low-income populations.

“The recently released Make America Healthy Again (MAHA) Commission Report assessment discusses the impact the current state of US diet quality, including consumption of UPFs, is having on the health of our nation and its youth. However, scientific backing for this assessment has recently come into question,” explains Jerold Mande, CEO of Nourish Science.

“Our study provides the missing link — the first analysis of recent national data that substantiates the striking nationwide prevalence of poor diet quality, regardless of sociodemographic status, and the urgent need to tackle this health crisis with science-based policies and programs.” 

A new framework for policy and progress

The study’s authors further emphasize that enhancing diet quality must be a national priority. They argue that implementing clear, science-based metrics will enable federal agencies to track progress and take responsibility for improving public health outcomes.

The proposed measurement framework offers policymakers and public health stakeholders a scalable tool to evaluate and improve federally funded nutrition interventions. Advocates say this approach could help shape a more data-responsive and equitable food system — one that aligns food security efforts with actual health improvements.

As Congress prepares for potential changes to SNAP and related programming, experts say the findings should serve as a wake-up call.

“Unfortunately, the critical SNAP-Ed program may be repealed under the ‘Big Beautiful Bill,’ which will move the US farther away from improving diet quality and meeting the goals of the MAHA movement by excluding low-income people who are at high risk for developing nutrition-related chronic disease,” Mande concludes.