What’s the Skinny, or Rather the Fat, on Ultra-Processed Foods?

(Image credit to Anna Shvets via Pexels.com)

My partner and I are both 46 years old, and we often talk about how much has changed since we were born, especially when it comes to technology and convenience. But it wasn’t until recently that I started to view food through this lens of change. While I wasn’t raised in a household with a lot of processed foods, I had friends who would feast on Mac and cheese, sugary cereals, and the most sought-after of frozen desserts of the 1990’s, the ice cream Snickers bar! 

Ahhhhh. . . Remember when the Snickers Ice Cream Bar arrived on the scene. . . . .?

Ahhhh. . . remember the 90s!?

But overall, diets of the past consisted more of whole foods than processed foods. Time has changed that. According to data from 2018, ultra-processed foods (UPF) make up more than half of the total dietary-energy consumed in the United States. (1) You notice I used the word “ultra-processed” not just “processed.” So what the heck is the difference between a processed food and an ultra-processed food (UPF), and what does it matter if half our diet originates from UPF anyway? Well, let’s dig in!

What is Processed food?

At its most basic, processed food is a food that has been altered in any way, not just nutritionally. From pasteurization to vacuum sealing, and freezing to packaging, processing happens along a wide spectrum. 

The Nova Food Classification System

Because of the large scope and general definition of “processed” food, a Brazilian nutrition scientist, Carlos Monteiro, developed the Nova system of processed food classification in 2009. Dr. Monteiro is Professor of Nutrition and Public Health at the University of Sao Paulo, Brazil, and is a current member of the WHO Nutrition Guidance Expert Advisory Group and the scientific advisory committee of the International Obesity Task Force.

While the Nova system of processed food classification is not recognized by the United States Department of Agriculture (USDA) or US Food and Drug Administration (FDA), the Nova classification system is recognized and used by the World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations. Much of the recent academic research into ultra-processed foods (UPFs) uses the Nova classification system as well.

Many food classification systems have been developed that pay special attention to processing, but today we are only delving into the Nova classification system as it has received support from the international academic community, and was used in one of the only clinical trials examining the health effects of ultra-processed foods, that we will get into later in this post. 

I’m going to give you a simplified explanation of the Nova system, but if you want to delve deeper into it I recommend you check out the 2019 article “Ultra-processed foods: what they are and how to identify them.” (2) 

The Categories of Processed Food (Nova)
Four categories of processed foods comprise the Nova system.

GROUP 1: Unprocessed and minimally processed foods

This group includes unadulterated, natural food items that have undergone minimal to no processing. Minimal processing usually involves changes to a food that increase its longevity or safety, but do not alter the nutritional content at all. 

Think of such processes as refrigeration, vacuum sealing, fermentation, pasteurization, and packaging etc. Unless you are purchasing exclusively from local farmers, much of your fruits, vegetables, nuts, grains, meats, and milk will fall into Group 1. 

Group 2: Processed culinary ingredients 

Group 2 includes oils, fats, sugar, and salt. These foods undergo processing methods such as pressing, refining, grinding, milling, and drying.

The foods in this category are not meant to be eaten alone but are used in the preparation of other foods in both home and commercial kitchens.

Group 3: Processed foods

Group 3 is basically made up of any of the foods in Group 1 and Group 2 above that also have salts, sugars, or fats added to them. Foods in Group 3  usually have just a few ingredients, and no artificial colors or additives. 

Think of canned fruits and vegetables, juices, and some bread and cheeses. These processed foods are still recognizable to their origins and can be eaten alone or in combination with other foods.

Group 4: Ultra-processed foods

Ultra-processed foods can be categorized by ingredient and method. UPFs will not only include a lot of added sugars, salts, and fats, but they will also include additives and artificial ingredients. And their method of being made is highly industrialized. UPFs are often characterized by ingredients such as high-fructose corn syrup, invert sugar, maltodextrin, hydrogenated oils, etc that are of “no or rare culinary use” and used mainly in the manufacture of UPFS. (Remember, this is just a summary, the Nova paper referenced above goes into much greater detail).

How to Identify UPF

Keep in mind tho that food manufacturers are not required to document the extent to which a food product is processed, so currently, much of the onus still rests on the consumer. For instance, the division between “processed” and “ultra-processed” isn’t always immediately clear. Let’s look at a clarification provided by Monteiro et al,

“Industrial breads made only from wheat flour, water, salt and yeast are processed foods, while those whose list of ingredients also include emulsifiers or colours are ultra-processed. Plain steel-cut oats, plain corn flakes and shredded wheat are minimally processed foods, while the same foods are processed when they also contain sugar, and ultra-processed if they also contain flavours or colours.”

This confusing separation between “processed” and “ultra-processed,” that Monterio et all were trying to clarify in the statement above, came up in a conversation with the founder of the Eatiquette app. She brought up how “ice cream” is often categorized as a UPF, yet not ALL ice creams would accurately fall into this category. For example, Haagen-dazs’ vanilla ice cream has only 5 ingredients: cream, milk, sugar, egg yolks, and vanilla extract. This ice cream, which has no additives, artificial colors/flavors, or non-culinary ingredients, would fall into the processed category of foods, NOT the ultra-processed category. So yes, a little detective work needs to be done by consumers until we demand a change in labeling from food manufacturers and/or the regulatory agencies.

Benefits of Processing

Before we delve into some of the research that suggests UPF is detrimental to our health, let’s admit to the benefits. Ultra-processed foods are inexpensive, convenient, have a long shelf-life, provide some important nutrients (especially any fortified UPF), and are often manufactured and preserved in such a way as to be “relatively safe from the microbiological perspective.” (3) Regarding safety, there is an allure to eating safely processed foods when you consider the outbreaks of E. Coli infections associated with whole foods such as Romaine lettuce. 

It’s Ultra-processed; So What?!

Most research into processed or ultra-processed foods has been cohort studies and ecological studies.  (An ecological study has at least one variable that is measured at the group [i.e. population] level.) To date, only one randomized-controlled trial (RCT) has been conducted on the effects of UPF. RCTs are often considered the gold standard of epidemiological studies as they are more likely to show causality.  Much of the resulting data from the majority of studies on ultra-processed food has indicated an association between intake of ultra-processed foods and increased risk of mortality and weight gain. 

The Fat on UPF; the RCT

The study of most interest to me was a very small randomized controlled trial that was conducted in a lab! The results of this trial were published May 16, 2019 in a paper titled “Ultra-processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake.” (4)

Read that title again. . . the word “cause” is IN the title!! The authors of this study don’t just suggest there is an “association,” they believe their trial shows a cause. This is pretty cool!

One more thing about the title; the phrase “ad libitum” basically means the participants could consume AS MUCH food as they wanted: there was no limit on their food intake. 

What else makes this study special is that all 20 participants (it was a small, but well designed study) stayed in a lab setting for 28 days. This definitely reduces the subjective and often erroneous nature of “self-reporting.”  Participants were randomly assigned to either the ultra-processed food group or unprocessed food group for 2 weeks, and then switched groups for the remaining 2 weeks. Three meals a day were provided to all participants who were directed to eat as much or as little as they wanted with 60 minutes allotted for each meal. 

Graphical Abstract from

Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake

Matched, Calorie for Calorie

The genius part of this research trial was that the nutritional content was the same across both categories: calories, fat, carbohydrate, protein, fiber, sugars, and sodium were all matched. Since UPF are often low in fiber, the participants in the ultra-processed group were given a fiber supplement that was mixed into drinks. So the only difference in the diets was the SOURCE of the calories; ultra-processed or unprocessed. Oh, and the price - there was definitely a difference in the price of the meals. The authors explained,

“The weekly cost for ingredients to prepare 2,000 kcal/day of ultra-processed meals was estimated to be $106 versus $151 for the unprocessed meals as calculated using the cost of ingredients obtained from a local branch of a large supermarket chain.” (4)

How interesting!

And the Results???

The study found that on average the subjects who were fed the ultra-processed diet ate ~500 (the tilde symbol means “approximately” or “around”) more calories per day compared to the unprocessed diet. The macronutrients consumed most were carbohydrates and fats, not proteins. Body fat saw a statistically significant increase on the ultra-processed diets and a decrease on the unprocessed diet. The unprocessed diet also led to decreases in total cholesterol, and the hunger hormone, ghrelin, in comparison to the ultra-processed diet. And PYY, the appetite-suppressing hormone, increased on the unprocessed diet in comparison to the ultra-processed diet and baseline.

The authors present theories regarding why the diets resulted in statistically different results, as well as suggest future research topics to further address the effects of UPF on our health. If this post has piqued your intellectual appetite but you aren’t interested in reading the full academic paper, consider viewing this hour-long video called “Calories, Carbs, or Quality: What Matters Most for Body Weight” presented by Kevin D. Hall PhD, the lead researcher on the study in question.

This video is totally worth one hour of your time!

Plus, I promise there are more fun visuals than in this post!

What does this mean for you and me?!

This is just one study of many that are investigating the effect ultra-processed foods have on our health, and more are certain to follow. So what does this mean for you!? Well, similar to a statement in the research paper,

“Limiting consumption of ultra-processed foods may be an effective strategy for obesity prevention and treatment.” (5)

Additionally, whole foods are often nutrient-dense, without requiring any additives. Ultra-processed foods have a lot of short-term benefits, but we are now starting to see that they also may be associated with a lot of long-term detriments.

Am I encouraging you to toss all the UPF out of your cupboard? Not just yet!

But how about this. . . really take a good long look at how much ultra-processed food you consume. Maybe start keeping a Processed Food Journal (this isn't calorie counting, it’s just food journaling). Does your diet, like most Americans, consist of 50% UPF? Or more? If so, consider reducing that percentage by swapping out ultra-processed foods with whole foods or at least less processed foods. I will do the same, and give tips in my next post about how to reduce your dependence on UPF!

Lastly - Retro-nasal Olfaction and Processing!

Jim’s favorite side dish!

Parboiled Long Grain Rice, Vermicelli (Wheat Flour, Durum Flour), Less Than 2% Of: Salt, Yeast Extract, Whey Protein Concentrate, Maltodextrin (Corn), Sugar, Onion Powder, Cheddar Cheese (Pasteurized Milk, Cheese Cultures, Salt, Enzymes), Broccoli, Asiago Cheese (Pasteurized Milk, Cheese Cultures, Salt, Enzymes), Potassium Chloride, Natural Flavors, Lactic Acid, Olive Oil, Disodium Inosinate, Disodium Guanylate, Parsley, Annatto (For Color), Vitamins and Minerals: Niacin, Ferric Orthophosphate (Iron), Ferrous Sulfate (Iron), Riboflavin (Vitamin B2), Thiamine Mononitrate (Vitamin B1), Folic Acid. May Contain Soy and Sulfites

Some of the theories about why people consume more calories on an ultra-processed diet is that the processed foods break down quicker in the mouth than unprocessed foods do. Think of how much chew-time a serving of quinoa takes to break down in comparison to one of my partner’s favorite cheddar broccoli Knorr rice sides!

And another absolutely intriguing theory I read about (tho I cannot recall where) was how retro-nasal olfaction is affected by ultra-processed foods. Retro-nasal olfaction is basically the smelling that occurs in our oral cavity while eating and drinking, as opposed to ortho-nasal olfaction that occurs outside of our mouth when sniffing.

Basically, because UPF breakdown so fast, we don’t have enough time to really sense and smell the food, so we continue to eat and eat! It’s just a theory, but sure is a freaking compelling one! So, when you are eating ultra-processed foods, at least try and savor them as much as you can and then consider swapping them for less processed foods.

Until Next Time. . . Try a Journal

Keep a Processed Food Journal. Write down all the food you eat over a few days’ time and then try and categorize them according to the four Nova categories of food. Then estimate what percentage of your diet is made up of processed foods. I will do the same and report back! Until then, observe like a scientist and eat well!

References:

(1) “Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake: Cell Metabolism.” Accessed June 19, 2021. https://www.cell.com/cell-metabolism/fulltext/S1550-4131(19)30248-7?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1550413119302487%3Fshowall%3Dtrue.

(2) Monteiro, Carlos A., et al. “Ultra-Processed Foods: What They Are and How to Identify Them.” Public Health Nutrition, vol. 22, no. 5, Apr. 2019, pp. 936–41. Cambridge University Press, doi:10.1017/S1368980018003762.

(3) “Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake: Cell Metabolism.” Accessed June 19, 2021. https://www.cell.com/cell-metabolism/fulltext/S1550-4131(19)30248-7?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1550413119302487%3Fshowall%3Dtrue.

(4) Ibid

(5) Ibid