Ultra-processed food expert and nutrition scientist Kevin Hall resigns: What it means for research

The move comes after the scientist’s views on one of his recent publications about addiction to ultra-processed foods was censored.

In a post on X, Hall said: “I experienced censorship in the reporting of our research because of agency concerns that it did not appear to fully support preconceived narratives of my agency’s leadership about ultra-processed food addiction. I was hoping this was an aberration. So, weeks ago I wrote to my agency’s leadership expressing my concerns and requested time to discuss these issues, but I never received a response.”

After 21 years at my dream job, I’m very sad to announce my early retirement from the National Institutes of Health. My life’s work has been to scientifically study how our food environment affects what we eat, and how what we eat affects our physiology. Lately, I’ve focused on… pic.twitter.com/JSybxCujDH

— Kevin Hall (@KevinH_PhD) April 16, 2025

He said that given the bipartisan support to preventing diet-related chronic diseases, he had hoped to expand the research programme. He went on to say: “The NIH …allows scientists to take risks, form unique collaborations, and do studies difficult to conduct elsewhere.”

What did the study say?

Last month, the agency published a study that showed that the dopamine-hit after eating ultra-processed foods was not similar to what is seen in drug users as previously thought. Brain scans have shown that the levels of the feel-good hormone dopamine increases in the brain when people take addictive drugs, pushing them to go for it again and again.

It was believed that the dopamine-reward mechanism may be similarly triggered by foods high in fats, sugars, and salts, driving people to consume more and more. In their latest research, Dr Hall’s team, however, did not see significant changes in the dopamine levels in brain scans after consuming ultra-processed foods. Those who did show very small increases in their dopamine level, however, found their milkshakes to be more pleasurable and ate more cookies later on.

However, researchers put in a caveat that the machine used to study the brain, while very effective for tracking the large dopamine changes caused by drugs, might not have been sensitive to detect small changes. So the research raised more questions about what makes these foods more addictive.

What are ultra-processed foods?

Ultra-processed foods are industrially produced foods containing ingredients not available in home kitchens, such as breakfast cereals, biscuits, chicken nuggets and other frozen foods. These tend to contain high levels of salts, sugars, and fats, especially harmful fats such as trans fats. While many naturally occurring fruits, vegetables, or nuts might contain high levels of either fats or carbohydrates, they rarely ever contain both unlike ultra-processed foods.

These foods have been known to cause addictive behaviours in people and are known to lead to diet-related chronic diseases such as obesity, hypertension, and diabetes among others.