A popular U.S. brand of potato chips once promoted itself with the slogan, “betcha can’t eat just one!”
Maybe that’s because potato chips, like so many foods in the American diet, can pack a mix of ingredients apt to light up people’s brain-reward neural circuitry and overpower mechanisms that are supposed to signal when we’ve had enough to eat.
Researchers call this class of foods — often processed foods or sweets with alluring combinations of fat, sugar, carbohydrates and sodium — “hyper-palatable.”
While a slew of films, popular books and academic studies have addressed hyper-palatable foods over the past 15 or so years, none has yet to offer a broadly accepted quantitative definition of just what constitutes a hyper-palatable food.
Research published today in Obesity and presented at 4:45 PM PST at the 7th Annual Obesity Journal Symposium at ObesityWeek at the Mandalay Bay South Convention Centre in Las Vegas will change that, offering specific metrics that might qualify foods as hyper-palatable — and finding most foods consumed in the United States meet these criteria.
“Multiple documentaries have pointed out that food companies have very well-designed formulas for these types of foods to make them palatable and essentially enhance consumption,” said lead author Tera Fazzino, assistant professor of psychology at the University of Kansas and associate director of the Cofrin Logan Center for Addiction Research and Treatment at KU’s Life Span Institute.
“But these definitions are virtually unknown to the scientific community, which is a major limitation.
If there’s no standardized definition, we can’t compare across studies — we’ve just typically used descriptive definitions like ‘sweets,’ ‘desserts’ and ‘fast foods.’
That type of descriptive definition isn’t specific to the actual mechanisms by which the ingredients lead to this enhanced palatability.
This has been a substantial limitation in the field I thought was important to try to address.”
Fazzino and her KU coauthors — Kaitlyn Rohde, research assistant at the Cofrin Logan Center and Debra K. Sullivan of the Department of Dietetics and Nutrition at the University of Kansas Medical Center — sought to define criteria for hyperpalatable foods by conducting a literature review, and then using nutrition software and applying their definition to 7,757 food items in the U.S. Department of Agriculture’s Food and Nutrient Database for Dietary Studies (FNDDS).
“We essentially took all of the descriptive definitions of the foods from the literature — for example Oreos or mac and cheese — and we entered these one by one into a nutrition program that is very careful in how it quantifies a food’s ingredients,” said Fazzino.
“This nutrition software essentially provides in fine-grained detail a data set that specifies how many calories per serving are in this food, and how much fat, sodium, sugar, carbohydrates, fiber and all sorts of other things.”
The team looked for items that met criteria established by their literature review as enhancing palatability, specifically where “the synergy between key ingredients in a food creates an artificially enhanced palatability experience that is greater than any key ingredient would produce alone.”
They identified these synergies with specific values applied to three “clusters:” combinations of fat and sodium (such as hot dogs or bacon); combinations of fat and simple sugars (like cake, ice cream and brownies); and combinations of carbohydrates and sodium (such as crackers, pretzels and popcorn).
“Essentially, we wanted to identify foods that appear to cluster together with what appeared to be like similar levels of at least two ingredients, because that’s the theoretical basis for inducing the synergistic palatability effect,” said Fazzino.
“Through a visualization process, we were able to see there were essentially three types of foods that appeared to cluster together in terms of their ingredients.”
Once the researchers were able to quantify characteristics of hyper-palatability, they applied their definition to foods cataloged in the FNDDS.
They hoped to discover how prevalent hyper-palatable foods have become in the American diet.
The authors found that 62% of foods in the FNDDS met the criteria for at least one of the three clusters they’d identified.
Most (70%) of those foods that qualified were high in fat and sodium, such as meat dishes or egg and milk-based foods like omelets or cheese dips.
Some 25% of the hyperpalatable foods were high in fat and sugar, and 16% of these foods were high in carbohydrates and sodium. Less than 10% qualified in more than one cluster.
Most shockingly, items labeled as reduced or no fat, sugar, salt or calories represented 5% of hyperpalatable foods identified by the researchers.
Moreover, of all items labeled as low/reduced/no sugar, fat, sodium, and/or sugar in the FNDDS, 49% met the criteria for being hyper-palatable.
Fazzino said someday the team’s research might offer guidance to policymakers hoping to warn consumers about hyper-palatable foods and improve the diet of children.
“We need more evidence — but eventually if research begins to support that these foods may be particularly problematic for society, I think that could warrant something like a food label saying ‘this is hyperpalatable,'” she said.
“We might even think about the restriction of certain types of foods that are available in certain places — for example, in elementary school cafeterias for kids whose brains are still developing and who may be impacted by these types of foods.”
Fazzino plans to build on this work by analyzing how the ubiquity of hyper-palatable foods in the U.S. diet compares to foods available in other nations. She recently applied for a grant to compare American foods to those consumed in southern Italy, where a Mediterranean diet is prevalent.
Deﬁning ultra-processed foods
Almost all foods are processed to some extent, if only by preservation, and it is therefore unhelpful to criticise foods as being ‘processed’.
A number of food classiﬁcations have been devised that pay special attention to types of pro- cessing. A systematic review has shown that, of these, NOVA is the most speciﬁc, coherent, clear, comprehensive and workable.
NOVA classiﬁes all foods and food products into four groups according to the extent and purpose of the industrial processing they undergo.
It considers all physical, biological and chemical methods used during the food manufacturing process, including the use of additives.
A summary of the types and purposes of the industrial processes that deﬁne each of the four NOVA groups, shown below, makes it easy to understand the unique features of ultra-processed foods and to appreciate the health concerns associated with their consumption. Full deﬁnitions and lists of examples of each of the four NOVA groups are provided in the online supplementary material,
Supplemental Table 1.
Non-ultra-processed food groups
Minimally processed foods, that together with unpro- cessed foods make up NOVA group 1, are unprocessed foods altered by industrial processes such as removal of inedible or unwanted parts, drying, crushing, grinding, fractioning, roasting, boiling, pasteurization, refrigeration, freezing, placing in containers, vacuum packaging or non- alcoholic fermentation. None of these processes add salt, sugar, oils or fats, or other food substances to the original food. Their main aim is to extend the life of grains (cer-als), legumes (pulses), vegetables, fruits, nuts, milk, meat and other foods, enabling their storage for longer use, and often to make their preparation easier or more diverse.
NOVA group 2 is of processed culinary ingredients. These are substances obtained directly from group 1 foods or from nature, like oils and fats, sugar and salt.
They are created by industrial processes such as pressing, cen- trifuging, reﬁning, extracting or mining, and their use is in the preparation, seasoning and cooking of group 1 foods. NOVA group 3 is of processed foods.
These are industrial products made by adding salt, sugar or other substance found in group 2 to group 1 foods, using preservation methods such as canning and bottling, and, in the case of breads and cheeses, using non-alcoholic fermentation.
Food processing here aims to increase the durability of group 1 foods and make them more enjoy-able by modifying or enhancing their sensory qualities.
Traditional and long-established dietary patterns all over the world, including those known to promote long and healthy lives such as those in Mediterranean countries Japan and Korea, have been and are based on dishes and meals made from a variety of unprocessed or minimally processed plant foods, prepared, seasoned and cooked with processed culinary ingredients and com- plemented with processed foods.
The ultra-processed food group
Ultra-processed foods are formulations of ingredients, mostly of exclusive industrial use, that result from a series of industrial processes (hence ‘ultra-processed’).
Processes enabling the manufacture of ultra-processed foods involve several steps and different industries. It starts with the fractioning of whole foods into substances that include sugars, oils and fats, proteins, starches and ﬁbre. T
hese substances are often obtained from a few high-yield plant foods (corn, wheat, soya, cane or beet) and from puréeing or grinding animal carcasses, usually from intensive livestock farming. Some of these substances are then submitted to hydrolysis, or hydrogenation, or other chemical modiﬁcations.
Subsequent processes involve the assembly of unmodiﬁed and modiﬁed food substances with little if any whole food using industrial techniques such as extrusion, moulding and pre-frying. Colours, ﬂavours, emulsiﬁers and other additives are frequently added to make the ﬁnal pro- duct palatable or hyper-palatable. Processes end with sophisticated packaging usually with synthetic materials.
Sugar, oils and fats, and salt, used to make processed foods, are often ingredients of ultra-processed foods, gen- erally in combination. Additives that prolong product dura- tion, protect original properties and prevent proliferation of micro-organisms may be used in both processed and ultra- processed foods, as well as in processed culinary ingre- dients, and, infrequently, in minimally processed foods.
Ingredients that are characteristic of ultra-processed foods can be divided into food substances of no or rare culinary use and classes of additives whose function is to make the ﬁnal product palatable or often hyper-palatable (‘cosmetic additives’). Food substances of no or rare
How to identify ultra-processed foods
culinary use, and used only in the manufacture of ultra- processed foods, include varieties of sugars (fructose, high-fructose corn syrup, ‘fruit juice concentrates’, invert sugar, maltodextrin, dextrose, lactose), modiﬁed oils (hydrogenated or interesteriﬁed oils) and protein sources (hydrolysed proteins, soya protein isolate, gluten, casein, whey protein and ‘mechanically separated meat’).
Cosmetic additives, also used only in the manufacture of ultra- processed foods, are ﬂavours, ﬂavour enhancers, colours, emulsiﬁers, emulsifying salts, sweeteners, thickeners, and anti-foaming, bulking, carbonating, foaming, gelling and glazing agents.
These classes of additives disguise undesirable sensory properties created by ingredients, processes or packaging used in the manufacture of ultra- processed foods, or else give the ﬁnal product sensory properties especially attractive to see, taste, smell and/ or touch.
Ultra-processed foods include carbonated soft drinks; sweet or savoury packaged snacks; chocolate, candies (confectionery); ice cream; mass-produced packaged breads and buns; margarines and other spreads; cookies (biscuits), pastries, cakes and cake mixes; breakfast ‘cereals’; pre-prepared pies and pasta and pizza dishes; poultry and ﬁsh ‘nuggets’ and ‘sticks’, sausages, burgers, hot dogs and other reconstituted meat products; pow- dered and packaged ‘instant’ soups, noodles and desserts; and many other products (see online supplementary material, Supplemental Table 1).
Processes and ingredients used for the manufacture of ultra-processed foods are designed to create highly proﬁtable products (low-cost ingredients, long shelf-life, branded products) which are liable to displace all other NOVA food groups. Their convenience (imperishable, ready-to-consume), hyper-palatability, branding and ownership by transnational corporations, and aggressive marketing give ultra-processed foods enormous market advantages over all other NOVA food groups.
Marketing strategies used worldwide include vivid packaging, health claims, special deals with retailers to secure prime shelf space, establishment of franchised catering outlets, and campaigns using social, electronic, broadcast and print media, including to children and in schools, often with vast budgets. All this explains why ultra-processed foods have been successful in displacing unprocessed or minimally processed foods and freshly prepared dishes and meals – or ‘real food’ – in most parts of the world(7,45–47).
The nature of the processes and ingredients used in their manufacture, and their displacement of unprocessed or minimally processed foods and freshly prepared dishes and meals, make ultra-processed foods intrinsically unhealthy. The disorders and diseases associated with diets largely made up from ultra-processed foods, and the mechanisms linking these diets to speciﬁc diseases, are described elsewhere. The displacement of ‘real food’ by ultra-processed foods is also a cause of social, cultural, economic, political and environmental disruption and crises. These are also described elsewhere.
Identifying ultra-processed foods
The food manufacturing industry is not obliged to state on food labels the processes used in its products and even less the purposes of these processes. In some cases, this can make conﬁdent identiﬁcation of ultra-processed foods difﬁcult for consumers, health professionals, policy makers and even for researchers.
There is of course no need to examine every food to know whether or not it belongs to the ultra-processed food group. As stated above, and to take a few examples, fresh vegetables, fruits, and starchy roots and tubers are obviously not ultra-processed; nor are pasteurized milk and chilled meat.
Plant oils, sugar and salt, typically used in culinary preparations in combination with unprocessed or minimally processed foods, are also not ultra- processed.
It is however not always immediately clear when some speciﬁc food products are ultra-processed or not. Exam- ples include breads and breakfast cereals.
Here the solution is to examine the ingredients labels that by law must be included on pre-packaged food and drink products.
Industrial breads made only from wheat ﬂour, water, salt and yeast are processed foods, while those whose lists 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.
Generally, the practical way to identify if a product is ultra-processed is to check to see if its list of ingredients contains at least one item characteristic of the ultra- processed food group, which is to say, either food sub- stances never or rarely used in kitchens, or classes of additives whose function is to make the ﬁnal product palatable or more appealing (‘cosmetic additives’).
Food substances not used in kitchens appear in the beginning or in the middle of the lists of ingredients of ultra-processed foods. These include hydrolysed proteins, soya protein isolate, gluten, casein, whey protein, ‘mechanically separated meat’, fructose, high-fructose corn syrup, ‘fruit juice concentrate’, invert sugar, maltodextrin, dextrose, lactose, soluble or insoluble ﬁbre, hydrogenated or interesteriﬁed oil; and also other sources of protein, carbohydrate or fat which are neither foods from NOVA group 1 or group 3, nor culinary ingredients from NOVA group 2. The presence in the list of ingredients of one or more of these food substances identiﬁes a product as ultra-processed.
Cosmetic additives are at the end of lists of ingredients of ultra-processed foods, together with other additives.
As said above, cosmetic additives include ﬂavours, ﬂavour enhancers, colours, emulsiﬁers, emulsifying salts, sweeteners, thickeners, and anti-foaming, bulking, carbonating, foaming, gelling and glazing agents.
The presence in the list of ingredients of one or more additives that belong to these classes of additives also identiﬁes a product as ultra- processed.
Although information in ingredients labels is not fully standardized in all countries, some of the most frequently used cosmetic additives such as ﬂavours, ﬂavour enhan- cers, colours and emulsiﬁers are usually easy to identify in ingredients lists.
They are often expressed as a class, such as ﬂavourings or natural ﬂavours or artiﬁcial ﬂavours; or their names are followed by their class, such as ‘mono- sodium glutamate (ﬂavour enhancer)’, or ‘caramel colour’, or ‘soya lecithin as emulsiﬁer’. Other cosmetic additives may be known to consumers, such as certain types of sweeteners like aspartame, cyclamate or compounds derived from stevia.
In any case, the UN Codex Alimentarius provides a regularly updated list of additives with their functional classes as well as an online search facility where both names and classes of additives can be browsed.
Most foods as purchased and consumed are processed to some extent. For this reason, accounts that are critical of ‘processed food’ are not useful. Diets restricted to unpro- cessed food would be less diverse and less secure. Foods beneﬁt, and are made more available, when processed by various harmless methods of preservation; and some processes enhance food quality, non-alcoholic fermenta- tion being an example.
Traditional and established cui- sines all over the world are based on dishes and meals prepared from unprocessed and minimally processed food together with processed culinary ingredients and pro- cessed foods. The issue is not processing.
It is ultra- processed foods, the fourth group in the NOVA system of food classiﬁcation.
Ultra-processed foods are not ‘real food’. As stated, they are formulations of food substances often modiﬁed by chemical processes and then assembled into ready-to-consume hyper-palatable food and drink products using ﬂavours, colours, emulsiﬁers and a myriad of other cosmetic additives.
Most are made and promoted by trans- national and other giant corporations. Their ultra- processing makes them highly proﬁtable, intensely appealing and intrinsically unhealthy.
The present commentary shows how to identify ultra- processed foods, and is designed for policy makers, researchers, health professionals, journalists and con- sumers.
Computer software and cell phone apps that scan and interpret food package barcodes should make this identiﬁcation even easier. A cell phone app created by the
non-proﬁt organization Open Food Facts, based in France, already enables consumers to identify among more than 145 000 packaged products the more than 75 000 that are ultra-processed.
- Tera L. Fazzino, Kaitlyn Rohde, Debra K. Sullivan. Hyper‐Palatable Foods: Development of a Quantitative Definition and Application to the US Food System Database. Obesity, 2019; 27 (11): 1761 DOI: 10.1002/oby.22639