Why Ultra-Processed Foods Are So Hard To Resist

Ultra-processed foods (UPFs) are everywhere—affordable, convenient, and always within arm's reach. But there's more to their irresistible appeal than just easy access. Here’s how UPFs manage to keep us coming back for more, bite after bite.

How much UPF are we eating?

Ultra-processed foods make up a substantial portion of diets in European countries. In Romania, Estonia, Croatia, Italy, and Hungary, UPFs account for 10% to 20% of the diet.¹ This percentage rises to around 25% in Portugal, Spain, Denmark, Czechia, Slovenia, and Greece.¹ In Belgium, Austria, France, Latvia, and Finland, approximately 30% of the diet consists of UPFs. In Sweden, this figure increases to more than 40%, while in the United Kingdom, it reaches nearly 60%.¹

Despite a relatively widespread belief — although not conclusively proven —that UPFs are harmful to health, they remain a significant part of our diets.² Scientific research has shown correlations between UPFs consumption and higher risks of various diseases, including obesity, asthma, specific cancers, cardiovascular disease and type 2 diabetes.^3,4 So, why do we continue to consume UPFs at such a fast rate, even when we suspect they might harm our health?

What drives our consumption of UPFs?

Processed foods have technically existed for centuries, but their production boomed in the late 18th and early 19th centuries, largely to meet the needs of militaries that required nutritious long-life foods.⁵ By the 1950s, processed foods such as margarine, flour and some tinned vegetables had become a staple in many kitchens, primarily due to their convenience. These foods generally last longer than fresh foods because of the additives and stabilisers added during processing.⁶  Food technology advanced and this basic processing evolved into something far more complex: the creation of ultra-processed foods (UPFs). 

Read more: What You Need to Know About Ultra-Processed Foods

These foods are engineered, coloured and reconstituted to be almost impossible to resist, targeting our senses and cravings in ways that go beyond simple hunger. Common processing practices include refining the flavour, altering texture, enhancing colour and improving the smell to make the food more appealing and encourage us to eat more. How do these techniques work and are they really making us consume more UPFs?

Taste

Food taste can be altered through a process known as flavour engineering, which uses chemistry to create both artificial and natural flavours. One common technique in this process is identifying the “bliss point” - the sensory profile where a person enjoys the food the most. For example, sugar is added to a product incrementally until the consumer's enjoyment peaks. Adding more sugar from this point leads to a decline in enjoyment, creating a bell curve with a peak that is known as the bliss point.⁷

Flavour engineering, such as finding the bliss point, overstimulates taste buds, leading to the release of dopamine - a hormone secreted by the body when we experience something pleasurable.¹⁰ Our brains remember the action that triggered the dopamine rush and encourage us to repeat it, meaning we’re more likely to eat the product again. We don’t experience the same signals in our brains from eating a crunchy carrot or a piece of celery because our brains react differently to products with added sugars (such as UPFs), particularly when these sugars are present in higher quantities than found naturally in food.¹⁰

Policy actions in many countries are informed by reductionist approaches, which has led to an over-reliance on ‘nutrients-to-limit’ reformulation initiatives with potentially counter-productive outcomes.  This  includes  the  replacement  of  processed  ingredients  with  other  such ingredients, for example unhealthy fats with added sugars or artificial sweeteners, rather than with whole or minimally processed foods. (Source: Baker et al., 2020)

Texture

The texture of food can be altered during processing or with the addition of additives, and it plays a major role in the acceptance and appeal of a product.¹¹ Take your favourite ice cream from the local supermarket, for example. It gets its characteristic creaminess from processing and additives; without these, large, crunchy ice crystals would form, which would (probably) make the product less popular. Manufacturers achieve the creaminess by using machines that constantly stir the mixture during the freezing process.¹² Continuous stirring keeps the water molecules moving and prevents the small ice crystals that form during freezing from growing any larger. Additives help maintain the creamy texture of ice cream as it melts. Ingredients like gums, glycerines, and emulsifiers hold water close to them, which prevents the formation of large ice crystals.¹³

Texture has been shown to influence how fast and how much we eat, which is one reason why food manufacturers continue to manipulate it.¹⁴ Studies have shown that consumers tend to eat more soft-textured foods by weight and at a faster pace than harder foods, regardless of whether they are ultra-processed or minimally processed.^14,15 One explanation for this is the concept of “vanishing caloric density”. Foods that disappear quickly in your mouth trick your brain into thinking you’ve eaten less than you actually have, leading to a sense that you’re not full, resulting in you eating more.^16,17 A great example of this is Cheetos, which feel like they melt in your mouth.¹⁸

Read more: How Does Texture Affect the Way We Eat?

Colour

We all heard the saying “you eat with your eyes” - the idea that visual stimuli such as colour affects our perception of flavour, satiation, and calorie intake.^19,20 Humans - including children - subconsciously associate specific colours with distinct flavours: red is linked with sweetness, yellow and green with sourness, and brown and black with bitterness.²¹ Additionally, the colour of food influences our perception of its nutritional value. For example, red foods are perceived as being more energy dense than green alternatives - and the intensity of colour can shape our expectations about the quality and strength of flavour.²² 

When food colour is manipulated so too is our understanding of what we’re buying. Bright colours are associated with fresh and flavoursome foods, but colourings and additives can make UPFs appear unnaturally bright, giving the impression they are fresher than they actually are. For example, sodium nitrate - a white solid similar to salt - is added to cured meats for preservation and flavour but it also alters the meat's colour, making it appear pink or red and, therefore, more fresh to the consumer.^23,24 As a result, the use of artificial colouring can lead consumers to believe they are purchasing a fresher product than they might otherwise think."

Read more: How Does Colour Affect The Way We Eat?

All of us subconsciously associate certain colours with distinct tastes and flavours. For most people, red is associated with sweetness, yellow and green with sourness, white with salt, and brown and black with bitterness. Lianyungang, Jiangsu Province of China. (Photo by Geng Yuhe/VCG via Getty Images)

Sound and smell

Our senses never act alone, so while it might seem like sound and smell are small players compared to taste, touch, and sight, they play crucial roles in encouraging consumers to eat more.

Sound has been recognised as a desirable food trait for more than three decades. For example, in 1989 Doritos released a commercial featuring Jay Leno which described the company’s secret ingredient as “crunch”.²⁵ Crunchiness is often perceived as a marker of freshness—think of how crunchy lettuce seems fresher than limp leaves. A 2005 study found that louder crunches led participants to perceive the product (Pringle crisps in this case) to be around 15% fresher than quieter alternatives - and this link was used to explain why crunchy foods like crisps appeal to humans.²⁶

The loudness of food can also affect product enjoyment and trigger release of dopamine in our brains that makes us want to eat more.²⁶ For example, Magnum customers once complained that the chocolate on the outside of the ice cream broke into shards that then melted on clothing, making them dirty, while the product was being eaten.²⁷ In response Unilever set to work creating a chocolate casing that better stuck to the ice cream. However, customers complained again once the product was launched - this time that the crunch of the chocolate shell associated with a Magnum ice cream was gone. Unilever returned to the original recipe, and today consumers are gifted with ice cream adverts that include distinctive loud cracks as the Magnum is bitten into.

Smell also plays a significant role in influencing consumer behaviour. Artificial scents can be added to products to create a feeling of familiarity or spark dopamine responses in our brain that trigger cravings. For instance, food processors add meat smells to plant-based alternatives to make consumers believe the products are not that different from the real thing.²⁸ In other cases, foods with no natural aroma - such as ice creams that are too cold to release their chocolate and caramel scents - have manufacturers adding caramel fragrances to their packaging. When the plastic is opened, these scents are released, triggering a dopamine response understood as craving and making the consumer experience the ice cream flavour more intensely. The triggers of familiarity, craving and flavour intensity all encourage consumers to eat more.¹³

Read more: How Does Smell Affect the Way We Experience Food? and How Do Sound and Music Affect the Way We Eat?

What does this mean for consumption habits?

Ultra-processed foods are carefully engineered to possess humans’ favourite food qualities - such as the ‘bliss point’ of flavour, smooth textures, bright colours, strong aromas and even sounds. These attributes make the foods’ flavour seem more intense, trigger dopamine responses in the brain understood as cravings, trick the brain into thinking the body has eaten fewer calories than it actually has, and make the food seem more fresh and easy to eat. Altering the foods humans eat in this way has ultimately led to greater consumption of UPFs and in higher quantities.