Prominent Ultra-Processed Food Researcher Leaves NIH, Alleges Censorship

The Washington Post

15:00 JST, April 18, 2025

Six years ago, Kevin Hall led a landmark study providing the most compelling evidence to date that ultra-processed foods are harmful to Americans’ health.

So when Robert F. Kennedy Jr.’s Make America Healthy Again movement – an effort to combat chronic disease and childhood illness – gained steam, he was hopeful the nation’s biomedical research agency would prioritize more of his studies to understand the root causes of metabolic diseases.

But just two months into Kennedy’s tenure as the nation’s top health official, the longtime National Institutes of Health researcher said he is skeptical that he will be allowed to do his work free from political interference. Those concerns drove him to take the federal government’s early retirement offer, he said on social media this week, walking away from what he called 21 years at his “dream job.”

In an interview, Hall said he was worried that the Department of Health and Human Services might try to suppress future findings from his research into ultra-processed foods if they did not fit the Trump administration’s political agenda.

“I was hopeful that we would have more resources and opportunities to do the kinds of things that they’ve talked about,” he said. “But based on everything I’ve seen so far, I think they’re clearly going to be meddling in our research and the reporting of our results.”

Hall’s decision comes as Kennedy has made overhauling the nation’s food supply one of his core priorities – a notion that has found support on both the right and the left. But Kennedy has remained a polarizing figure, and public health experts and Democrats have been alarmed by his purge of the federal health workforce and his response to the measles outbreak.

In a statement, HHS pushed back on Hall’s claims.

“It’s disappointing that this individual is fabricating false claims,” HHS said in a written statement. “NIH scientists have, and will, continue to conduct interviews regarding their research through written responses or other means. We remain committed to promoting gold-standard research and advancing public health priorities.”

Around the globe, some countries have issued dietary guidelines explicitly urging people to avoid ultra-processed foods. In the United States, lawmakers on both sides of the political aisle have blamed ultra-processed foods for the obesity and chronic disease epidemics and called on the federal government to more tightly regulate them. But it’s onerous and expensive to study the industrially produced, hyper-palatable products that make up more than half of the calories Americans consume each day.

In an interview, Marion Nestle, an emeritus professor of nutrition, food studies and public health at New York University, said Hall’s departure from the NIH is a devastating blow to nutrition and public health research.

“I’m shocked,” she said. “I think he’s doing some of the most important work that’s been done in nutrition in decades. Somebody like him ought to be completely supported by the MAHA people – and the fact that they’re not supporting him puts the whole thing into question.”

Hall is in the midst of another study to identify the precise mechanisms that make ultra-processed foods harmful – research that he’s transferring over to another investigator and is expected to be completed as early as this year. But his reservations about remaining in government appeared to be percolating for several weeks.

In late March, Hall wrote an email to Kennedy, as well as senior HHS and NIH officials, with the subject line: “likely retirement of NIH scientist studying mechanisms of ultra-processed food.” The Washington Post obtained a copy of the email; it was not clear if Kennedy saw the message.

In the email, Hall wrote that he had circulated plans for how the government could “quickly and efficiently” obtain the data needed to understand how the nation’s food is making Americans sick. But he hadn’t received a response to his proposal, he wrote.

He also wrote in his messaging announcing his resignation and the email that he had experienced incidents of “censorship.” He alleged in his email that HHS contacted a New York Times reporter to downplay the results of his study published in March suggesting ultra-processed foods were not addictive in the same way as drugs. He also asserted that written responses sent to the reporter had been edited without his approval.

“These experiences have led me to believe that NIH may be a difficult place to continue the gold-standard unbiased science required to inform the needed transformation of our food supply to make Americans healthy,” Hall wrote in the email.

A New York Times spokeswoman referred questions to the newspaper’s coverage of Hall’s resignation. A story posted Wednesday stated that the Times’s request for a phone interview with Hall about the study was denied. According to the Times, the NIH let him answer questions in writing several days later, and the answers were sent to the newspaper through the NIH press office. Hall said in the email that those responses had been edited without his sign-off in a manner that downplayed the significance of his findings.

In a statement, the HHS wrote that “any attempt to paint this as censorship is a deliberate distortion of the facts.”

Before Hall’s 2019 study, many researchers had speculated that ultra-processed foods were a driving force in the obesity epidemic. They argued that ultra-processed foods like candy bars, potato chips, frozen meals, sugary breakfast cereals and soft drinks were not real food but “industrial formulations” designed by manufacturers to achieve a certain “bliss point,” which causes people to crave and overeat them. These foods typically contain many chemical additives not commonly used in home kitchens, like emulsifiers, artificial sweeteners, colors, stabilizers and preservatives.

Hall had been skeptical of the idea that ultra-processed foods could drive people to overeat. So he designed a rigorous clinical trial to compare what happened when people were fed a diet of mostly ultra-processed foods and a diet of mostly homemade, unprocessed foods. Both diets were matched for nutrients like salt, sugar, fat and fiber.

Hall was shocked by his findings. When people ate the ultra-processed diet, they consumed significantly more calories – about 500 more calories a day compared to when they ate the unprocessed diet. They also quickly gained weight and body fat.

Hall’s findings created a paradigm shift in the nutrition world, forcing many health experts to conclude that it’s not just the large amount of salt, sugar and fat in our diets that is making people sick, but the way food is industrially processed and the sheer number of additives it contains.

Hall, however, has previously said he believes it’s a mistake to demonize all ultra-processed foods. These foods make up a large share of the calories people consume in part because they are tasty, convenient and affordable, Hall said.

Some ultra-processed foods, like doughnuts and soft drinks, may be worse than others, like breakfast cereals and instant oatmeal, which at least have fiber, vitamins, and other important nutrients, Hall said. And if food manufacturers understood exactly what it is that makes ultra-processed foods so harmful, he has said, then perhaps they could reformulate their products.