Twenty-year-old Sam Srisatta is dedicating a month of his life to science, participating in a groundbreaking study that could shape the future of U.S. dietary guidelines and regulations on ultraprocessed foods, which currently make up nearly 70% of the American diet. Srisatta’s involvement in this study highlights the growing concerns about the health impacts of ultraprocessed foods, as well as the lack of clear policy to address the issue.
A Month-Long Clinical Trial to Investigate the Effects of Ultraprocessed Foods
Each morning, Srisatta follows a strict routine at the NIH Clinical Center in Bethesda, Maryland. Nurses track his vital signs, including weight, blood pressure, and even bowel movements, while blood is drawn to monitor his body’s reaction to the food he’s consuming. Some days, Srisatta rests in a chamber that measures his oxygen and carbon dioxide output to calculate his calorie burn. After these tests, he has 15 minutes to eat breakfast before the leftovers are weighed, recorded, and analyzed. Lunch and dinner offer more flexibility, but his meals are also carefully measured, and his vital signs are rechecked.
Srisatta is one of 36 volunteers participating in a unique randomized clinical trial led by Dr. Kevin Hall, a senior investigator at the National Institute of Diabetes and Digestive and Kidney Diseases. The goal of the study is to understand the health consequences of consuming different types of ultraprocessed foods, which are industrially manufactured and contain ingredients not typically found in home kitchens.
What Are Ultraprocessed Foods and Why Are They Harmful?
Ultraprocessed foods are made from refined ingredients and additives that enhance flavor, texture, and shelf-life, often through the combination of sugars, fats, and salt designed to hit a food’s “bliss point.” These foods may be irresistible, much like the iconic slogan from Lay’s potato chips: “Betcha can’t eat just one.”
Over the years, food scientists have refined these formulations, making them even more difficult to resist. Unfortunately, research has shown that a diet high in ultraprocessed foods can increase the risk of obesity and chronic diseases, including cancer, heart disease, type 2 diabetes, and depression. In fact, diet-related conditions account for at least half of all U.S. deaths, disproportionately affecting Black, Indigenous, low-income, and rural Americans. These conditions also contribute to the staggering $4.5 trillion in annual health care costs, according to U.S. Food and Drug Administration (FDA) officials.
The Link Between Ultraprocessed Foods and Obesity
A major concern with ultraprocessed foods is their link to overeating. Studies have shown that people tend to consume more calories when eating these foods compared to minimally processed options, despite both diets containing the same caloric intake. In one study led by Dr. Hall, participants ate an average of 500 more calories per day on an ultraprocessed diet, resulting in weight gain of nearly 2 pounds per week. A similar study in Japan found even greater calorie intake increases among those on ultraprocessed diets.
“The big question,” Hall says, “is why do people overeat when consuming ultraprocessed foods? We need to understand the mechanisms behind this so that we can give regulators and policymakers the tools they need to make informed decisions about food labeling and public health.”
Ultraprocessed Foods and the US Obesity Epidemic
Obesity has become a global epidemic, with the World Health Organization predicting that more than half the world’s population will be overweight or obese by 2035. In the U.S., nearly 260 million people are projected to be obese by 2050, unless immediate policy changes are implemented. For the first time, the U.S. Dietary Guidelines for 2025-2030 will specifically address ultraprocessed foods, with the goal of providing clear guidance on their role in the obesity crisis.
These guidelines will shape federal nutrition policies for the next five years. However, experts like Dr. Marion Nestle believe that the evidence linking ultraprocessed foods to poor health outcomes is already overwhelming. “Ultraprocessed foods are the most important concept to come into nutrition science since vitamins,” Nestle says, emphasizing that the addiction-like qualities of these foods are well-documented in research.
The Debate: Are All Ultraprocessed Foods Harmful?
Despite the evidence, scientists are still debating whether all ultraprocessed foods are equally harmful. Dr. Hall’s ongoing research aims to unravel this by studying the specific mechanisms that make some ultraprocessed foods more harmful than others. He hopes that identifying these factors will help guide future regulatory decisions, including potential changes to food labeling or new policies to reduce the consumption of harmful products.
One potential theory is that ultraprocessed foods are more energy-dense, meaning they pack more calories into smaller portions, which could encourage overeating. Another theory is that the “hyperpalatability” of these foods—designed to excite the taste buds—could drive excessive consumption. Hall’s team is testing these theories by modifying the ultraprocessed foods in the study, focusing on reducing their energy density and hyperpalatability.
Challenges in Research and Policy Change
Despite the growing body of evidence, creating effective policies to address ultraprocessed foods has been slow due to challenges in research. Dr. Walter Willett, a leading nutrition researcher at Harvard University, emphasizes the need for long-term studies in order to draw meaningful conclusions. Short-term trials, like the ones Hall has conducted, often fail to capture the full impact of ultraprocessed diets.
Moreover, defining what constitutes “ultraprocessed” food is still a point of contention. The classification of foods as ultraprocessed varies across studies, complicating efforts to create clear guidelines.
Looking Ahead: The Need for More Research
As the FDA and the U.S. Department of Agriculture work toward finalizing the 2025-2030 Dietary Guidelines, experts agree that more research is needed to understand the full impact of ultraprocessed foods on health. Dr. Hall’s study, while groundbreaking, is just one piece of the puzzle. His team hopes that continued research will lead to a better understanding of how ultraprocessed foods affect metabolism, obesity, and chronic disease—and ultimately inform policies that can improve public health.
Conclusion: Addressing the Ultraprocessed Food Crisis
As ultraprocessed foods continue to dominate the American diet, the need for clear, evidence-based policy is more urgent than ever. While current research provides compelling evidence of the harms associated with these foods, ongoing studies like Dr. Hall’s offer hope that science will eventually provide the answers needed to inform policy changes. In the meantime, it’s clear that reducing the consumption of ultraprocessed foods could be a critical step in improving the nation’s health.
