Ultra-processed Foods

What does the new "it" term mean?

One of the reasons I decided to start this newsletter was the emergence of the term “ultra-processed foods” in various publications. Part of me wanted to roll my eyes at the escalation of alarm over American food. The term “processed” has been thrown around for years along with the connotation that any food that is processed is bad for you. Technically, any type of cooking is a process. Alas, the term came to be code for “junk food”, which is also very loosely defined. All of that skepticism changed when I listened to an interview of Kevin Hall, a Ph.D. nutritional researcher at the National Institutes of Health, where he discussed his findings on the impact of ultra-processed foods on chronic health conditions such as obesity and diabetes. If you are interested in listening to the in-depth conversation check out Ground Truths by Eric Topol on Substack.

Before we dive into the NIH research findings, we should review the history of the term ultra-processed in relation to foods. Despite the recent adoption of the term in American media outlets, ultra-processed was first coined by Brazilian scientists in 2009. They sought to develop a classification system because, as I mentioned, it isn’t processing per se that is bad. Rather, it’s the type and intensity of that processing that can lead to negative health outcomes.¹ Most nutritional research had, up until that point, focused on individual nutrients, such as saturated fat or vitamins, not processing. It certainly was most of the focus when I completed my bachelor’s degree in Dietetics.

Despite the global medical community advocating for diets higher in fruits, vegetables and lean meats, rates of obesity continue to rise in both developed and developing nations. Worse still, no nation has been able to reverse obesity once it was able to develop. Here’s a scary statistic from a 2016 report written by the United Nations Global Panel on Agriculture and Food Systems for Nutrition, “If the direction of current policies remains the same, then estimates suggest that by 2030, the number of overweight and obese people will have increased from 1.33 billion in 2005 to 3.28 billion, around one third of the projected global population.”² That’s almost the size of the populations of China, India and the United States combined. Yikes!

Given the alarming obesity trends, the Brazilian scientists suggest examining foods through four different levels of processing. From their work the NOVA, which is not an acronym, classification was created.

Group 1 is unprocessed or minimally processed foods. These include edible parts of plants and animals. Processes to preserve these items without altering them, including refrigeration, freezing, non-alcoholic fermentation, drying and placing in vacuum packaging are examples of minimal processes. Basically, it’s fruits, vegetables, meat or fish without anything added to them. The ingredients we often use for home cooking in their original state.

Group 2 takes the ingredients from group 1 and processes them to create other culinary ingredients. Examples would include butter, cooking oils, sugar and salt. Most items in this category are not consumed by themselves. The key is group 2 ingredients are derived from real food.

Group 3 is where things start to get interesting. Foods within this group, processed foods, are developed with the purpose to extend shelf life or improve the taste and texture of foods in group 1. Now, we’re starting to alter the original food item. These items are created by combining group 1 and group 2 ingredients. They are recognizable derivatives of group 1 and 2 ingredients with short ingredient lists. In other words, when you read the ingredient statement it only contains a few ingredients and you recognize all of those ingredients without having a degree in food science. Cheese, canned fruit in syrup and freshly made bread without preservatives fall into this category.

Group 4 is the baddest of the bad, ultra-processed foods. Forget connections to real food, these items are often chemical concoctions of foods with additives. In addition to foods from Group 1 and 2, there’s a host of ingredients needing a food chemistry book to decode. They are designed to be convenient, attractive and profitable. Examples include soft drinks, candy, sweet or salty snacks and pre-prepared frozen dishes.

As you can see these classifications are quite broad. While noting this system is far from perfect, scientists have applied this system worldwide to conduct research using the same definitions. This allows nutritional researchers to study and compare health outcomes across a variety of global populations.

Now that we are clear on the definition of ultra-processed foods, we can review the research completed and underway at the NIH. Interestingly, Dr. Hall was initially a skeptic of the connection between ultra-processed foods and chronic health conditions. His first study was what I like to call a “proof-of-concept.” Any techies out there leading product management will understand this. He did a small scale pilot to determine if the hypothesis that diets high in ultra-processed foods increased obesity was true, or worthy of additional research.

Nutritional research is incredibly difficult because to really determine a link between certain foods, or diets and health outcomes the best methodology would require participants to live in an environment where all food, drink, exercise and other external factors are controlled over an extended period of time. Do you want to live in a lab for months or years? Me either. However, twenty people were willing to live in the NIH lab for one month. During that time, they were randomly assigned to one of two diets for two weeks. Then, they switched to the other diet the following two-week period. Diet 1 was comprised of unprocessed and minimally processed foods. Diet 2 was made up of ultra-processed foods. Meals were designed to contain similar amounts of fat, calories, fiber, sugar, sodium and cholesterol to remove the impact of individual nutrients.³

Participants were allowed to eat as much of each meal as they desired. Scientists weighed any uneaten food to determine total food consumption. The findings are not good news for Americans, considering a NYU study found 57% of the calories we consume are from the ultra-processed food category.⁴

While on the ultra-processed diet, participants ate 508 calories more per day than on the unprocessed diet. To gain a pound of fat requires the consumption of 3,500 excess calories. Doing a simple math exercise of 500 calories per day times 7 days and you can see one is easily consuming enough excess calories to gain a pound on the ultra-processed diet. So, it should come as no surprise that participants gained, on average, 0.9 kg, or 1.98 lbs., during the two weeks they were assigned to the ultra-processed diet. What is interesting is most of the increased caloric consumption came from eating more carbohydrates and fat, not protein.

With the proof-of-concept demonstrating a potential link between ultra-processed diets and obesity complete, the scientists at the NIH turned their attention to understanding why. What is it about ultra processed foods that might be causing us to eat more of them? Again, the ultra-processed and unprocessed meals in the first study contained equivalent amounts of calories and macronutrients. Why did participants eat more when presented with ultra-processed foods?

Research is still very much underway to answer this question. The early hypothesis, and subject of a follow-up study, is the energy density and hyperpalatabilty of foods influences how much we eat. I wrote about energy density in a previous post when the NIH released interim results late last year. As a reminder energy density, not to be confused with nutrient density, is when a food contains more calories per gram than minimally processed foods.

Hyperpalatable foods combine fat, sugar, carbohydrates and salt in ways that aren’t found in nature. A potato baked in an oven with no butter or seasoning, ok (not hyperpalatable). A potato sliced, fried in fat, whether oil or beef tallow, and doused with salt, yummy! And, some might say addictive. Research indicates the consumption of foods containing high amounts of sugar can trigger a dopamine, the “pleasure chemical”, response similar to drugs or alcohol. ⁵

Interim results from the ongoing NIH study show when participants were assigned a diet containing energy dense foods that are also hyper palatable they ate about 1,000 calories more per day than they did when eating a diet of minimally processed foods that are neither energy dense or hyperpalatable. Wow!

Before jumping to conclusions, we should wait until the full results are released. However, if true, this explains why it’s hard for some people to control food cravings. It also explains why it is so easy to gain weight after eating what appears to be a small amount of food. If foods are packed with calories in a single gram, it’s easy to eat a few bites and unwittingly consume a lot of calories.

So what to do? I don’t have easy answers. Besides the standard nutritionist advice of eating more fruits, vegetables and lean proteins, I would also say start reading labels for serving sizes. Then, measure out that amount. Other suggestions from the NIH researchers include building meals that contain unprocessed foods, group 1, with any ultra-processed foods, group 4. Lastly, look for low sodium versions of foods. That will help you to avoid hyperpalatable foods.

1. Monteiro CA. Nutrition and health. The issue is not food, nor nutrients, so much as processing. Public Health Nutrition. 2009;12(5):729-731. doi:10.1017/S1368980009005291

2. Global Panel on Agriculture and Food Systems for Nutrition (2016) Food Systems and Diets: Facing the Challenges of the 21st Century. London: Global Panel;

3. Kevin D. Hall, Alexis Ayuketah, Robert Brychta, Hongyi Cai, Thomas Cassimatis, Kong Y. Chen, Stephanie T. Chung, Elise Costa, Amber Courville, Valerie Darcey, Laura A. Fletcher, Ciaran G. Forde, Ahmed M. Gharib, Juen Guo, Rebecca Howard, Paule V. Joseph, Suzanne McGehee, Ronald Ouwerkerk, Klaudia Raisinger, Irene Rozga, Michael Stagliano, Mary Walter, Peter J. Walter, Shanna Yang, Megan Zhou, Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake, Cell Metabolism, Volume 30, Issue 1, 2019,Pages 67-77.e3,

4. Filippa Juul, Niyati Parekh, Euridice Martinez-Steele, Carlos Augusto Monteiro, Virginia W Chang, Ultra-processed food consumption among US adults from 2001 to 2018, The American Journal of Clinical Nutrition, Volume 115, Issue 1, 2022, Pages 211-221,

5. Liester, Mitchell, The Neurochemistry of Food Cravings, Psychology Today, March 14, 2024