Ultra-processed foods are catching a lot of attention these days for their role in the ever-growing obesity and diabetes epidemics.
To help you navigate the wild nutritional landscape, this article examines:
- What makes ultra-processed foods so bad for us?
- How can we identify ultra-processed foods quantitatively?
- Which foods and meals should we prioritise to avoid ultra-processed food?
Processing has allowed us to extract more energy from the available foods, and nutrients were always available in the foods we had available. But in recent times, we have taken this to new extremes to maximise energy and tend to miss out on nutrients.
Rather than avoiding ‘bad’ things in food we can identify foods that naturally contain the nutrients we need with less energy. Not only are these less processed, they also provide greater satiety and are harder to overeat.
- A Brief History of Ultra-Processed Foods
- Are All Processed Foods Bad?
- Ultra-Processed Food Is Creating a BIGGER Population
- What Does Ultra-Processed Food Do to the Brain?
- Dietary-Induced Thermogenesis
- We Extract More Energy from Ultra-Processed Foods
- We Eat More Ultra-Processed Foods
- We Expend Less Energy When We Consume Fat+Carb Ultra-processed Foods
- Why Are Ultra-Processed Foods Bad for Us?
- How Do We Define Ultra-Processed Foods?
- How Can You Tell If a Food Is Ultra-Processed?
- Is Fortification Good for Us?
- What Are the Most Processed Foods to Avoid?
- How Can You Develop the Habit of Avoiding Processed Foods?
A Brief History of Ultra-Processed Foods
Food processing is nothing new; we’ve just become better at it lately!
According to anthropologist Richard Wrangham, humans began incorporating fire as a cooking method around two million years ago. Not only did this enable us to consume more high-quality energy, but it also allowed us to get more nutrients from our food and for the food to taste better.
Wild animals spend most of their day consuming low-energy-density foods to simply get enough energy.
- The lion might spend a few hours chasing down prey and sleeping for the rest of the day.
- Ruminant animals like cows, goats, and sheep spend a lot more time eating grass because it has to ferment in each of their four stomachs so they can get their nutrients.
- Similarly, other non-ruminant animals like horses, chickens, deer, elk, and pigs must constantly graze to meet their energy and nutrient demands.
- Meanwhile, pandas—who only eat bamboo—and koalas—who eat eucalyptus leaves— spend most of their days eating but still struggle to get adequate energy.
Seeking out energy-dense foods and incorporating food processing has enabled our brains to grow and our digestive tracts to shrink. Key evolutions fuelled by increasing brain size—likely from the ability to consume more nutrients like protein and omega-3 fatty acids—have likely contributed to other key developments, like the ability to create tools to use for hunting, which has catalysed evolution even further.
Nonetheless, although cooking may degrade the nutrients in our food somewhat—as heat destroys delicate nutrients like vitamins and some fatty acids—it also enables us to consume enough extra energy and nutrients to offset what is lost.
Aside from cooking methods, incorporating herbs, spices, natural sweeteners, and even salt over the last several thousand years has undoubtedly increased how tasty food is and hence how much we can eat of them.
There are pros to food processing! However, while some processing can be helpful, it can quickly be taken to extremes.
Are All Processed Foods Bad?
Grandma’s comfort food recipes at Christmas and Thanksgiving combine various ingredients—particularly some combination of carbs and fat—into unique, tasty sensations. Think pies, cookies, cakes, cobblers, and casseroles… which is your favourite?
Because they provide us with energy from a combination of carbs and fat, these foods stimulate a unique dopamine release that makes us feel great and want seconds (and thirds and fourths). They might also make you want to have a nap!
Although these foods are tasty and delicious, we find little in the way of vitamins, minerals, essential fatty acids, and amino acids when we look at what’s inside them. These ‘foods’ are just tasty combinations of fat, sugar, starch, and other yummy flavourings that give you happiness in the moment… and a blood sugar crash not long after.
A hundred, ninety, eighty, and even seventy years ago, Grandma’s seasonal treats were just that—seasonal treats. But in recent times, we’ve solved food security, which has allowed us to create a wide array of these nutritionally poor, energy-dense comfort foods. They’re now available year-round, on demand. Subsequently, we have a shortage of nutrients in our food system despite abundant energy.
Modern agricultural technology, like synthetic fertilisers, industrialised farming practices, and food processing, has enabled us to create nutrient-poor, high-energy foods that many people feel almost addicted to.
Dr Kevin Hall, one of the foremost researchers in ultra-processed foods, recently spent most of his 15-minute talk at the Royal Society Meeting on the Causes of Obesity discussing technological advances that have radically changed our food system over the past century. You can watch Kevin’s talk from 2:01:19 in the video below.
Hall describes how we used technology to innovate ourselves of an impending food shortage in the face of a growing population. While we’ve managed to ensure we have plenty of energy, the nutrient content of our food is declining.
Additionally, innovative businesses ready to capitalise and turn a quick profit are more than happy to combine ultra-cheap subsidised ingredients to create irresistible food products.
Ultra-Processed Food Is Creating a BIGGER Population
The first agricultural revolution took place around 12,000 years ago. Here, humans transitioned from hunter-gatherers to agriculturalists, and we began domesticating plant and animal foods. In the Bible, Genesis 41 records the story of Joseph, who innovatively stored grain that allowed people to survive the coming famine.
This allowed us to prevent starvation and ensure food security by hoarding just a little more food than we needed. Not only has this ensured that we make it through the winter and famines (i.e., short-term survival), but it has also supported a human population that’s continued to grow in size and number (i.e., long-term survival).
Farming and domestication alone were enough to cause a gentle uptick in our population growth throughout the next few millennia. However, this growth was nothing compared to what we experienced when we discovered synthetic fertilisers created from natural gas just over a century ago, which has put this process into hyperdrive!
This process, known as the Harber-Bosch process, enabled us to fixate nitrogen into the soil. This effectively enables us to inject energy from methane gas into the ground to create synthetic fertilisers, catalysing the growth of plant products no matter the health of the soil. This ingenious invention has been dubbed the spark that ignited our ever-growing population explosion.
For more on the historical context that has led us to where we are now, see:
- How the Biggest Trends in Nutrition Influence How We Currently Eat
- What Lies Beyond the Nutritional Apocalypse?
At one time, crops had to be rotated each year to give the soil time to rest and nutrients a chance to reaccumulate in the soil. However, with the advancement of these fertilisers, crops could be grown essentially on demand.
Crops like corn, wheat, soy, and other high-demand grains that used to take a toll on the soil could now be grown cyclically without bounds. With the help of government subsidies, growing these crops became increasingly affordable, too.
Around the same time that the Harber-Bosch process was discovered, humans also figured out the process of hydrogenation. This process takes a fat in a liquid form—like canola or soybean oil—and turns it into a solid, similar to butter.
Not only did this make the plant seed oils that were now increasingly abundant more usable (think margarine), but it also made them more shelf stable. However, this came at the expense of the formation of trans fatty acids, which we’ve now linked to various diseases and modern disorders.
Aside from seed oils, these highly subsidised crops provided us with seemingly endless reserves of soy meal, corn meal, and wheat flour, which would serve as the basis for many highly processed ingredients.
As our reserves of corn, soy, wheat, and other cheap grains grew, we also learned how to transform the wastes we accumulated from processing them into usable ingredients. While a lot of this grain ‘silage’ goes to feeding cattle—an arguably unnatural part of their diet—others are added back into our food as bulking agents and even sweeteners.
Over time, food scientists realised they could combine these raw ingredients that were tasty on their own with one another for the double-dopamine response from fat and carbs we know—and love! So, while we at one time only thought these cheap grains could give us flour, we ended up with almost three times that in terms of raw ingredients when we consider seed oils.
What Does Ultra-Processed Food Do to the Brain?
The chart below (created using data from the US Department of Agriculture (USDA) Economic Research Service and the US Centres for Disease Control (CDC)) shows how obesity rates have taken off as our food has become an increasingly similar blend of fat and carbs!
In 2018, Dana Small and colleagues published Supra-Additive Effects of Combining Fat and Carbohydrate on Food Reward, which showed how we overvalue foods that combine these two macronutrients and elicit a supra-physiological dopamine response.
To see if Dana Small’s observation held up, we looked at the satiety response to non-fibre carbohydrates using our analysis of one hundred and fifty thousand days of food logging data from forty thousand people who have used Nutrient Optimiser.
Our results, shown in the chart below, align with Small’s findings! Here, we can see that we consume 23% more energy when our food contains about 45% of our calories from non-fibre carbs. Most of the rest of the energy comes from fat, and little energy is from fibre or protein.
As the chart below shows, the amount of energy from fat and carbs has increased since the second agricultural revolution of the 1960s, whereas protein has risen only marginally. Whether by luck or clever food science, we stumbled onto the magic formula that drives us to eat and buy more of these foods.
For more details on this lethal combination, see
Our analysis of Optimiser data also shows that we eat more when our food consists of less overall calories from protein and fibre and more comes from fat and non-fibre carbohydrates.
The chart below shows the energy distribution from fat and non-fibre carbs from our Optimiser data. Here, we see the average Optimiser consumes 64% of their energy from fat and carbs. For reference, the average population of 86% intake is out to the far right, which we know from the chart above aligns with the lowest satiety outcome! It’s no wonder we’re eating more than we need and are becoming increasingly obese and diabetic!
Dietary-induced thermogenesis, or the thermic effect of food (TEF), is the energy we expend to digest, absorb and metabolise a specific macronutrient in food.
The table below shows the thermic effect of the different dietary macronutrients we consume. It also shows the macronutrients in the order in which we metabolise them. This is a principle known as oxidative priority.
|Thermic Effect||15%||3%||20 – 35%||5 – 15%||3 – 15%|
As we can see, protein requires the most energy to metabolise than any other macronutrient.
While we can convert protein into our primary energy source, adenosine triphosphate (ATP), it is rather laborious. Additionally, it’s relatively inefficient, as so much energy is lost in the conversion. Thus, our bodies prefer to get their fuel from fat or carbs.
Meanwhile, carbs and fat have lower thermic effects, meaning we store them more easily, and they are more efficient energy sources. Whether we’re consuming our carbs and fat from whole foods or processed ones, this holds true. Because these are such ‘easy energy’ sources, we tend to direct our energy towards fat and carbs once we’ve got adequate protein.
For more on oxidative priority and the thermic effect, check out Oxidative Priority: The Key to Unlocking Your Fat Stores.
We Extract More Energy from Ultra-Processed Foods
We now see that even in whole foods, fat and carbs are more efficient energy sources than protein. But more processing makes it even easier to absorb energy with even fewer losses.
Whole, unprocessed foods contain food components like fibre that we cannot break down. However, processing and refining make energy sources—like starch, sugar, and fat—even more efficient.
Aside from allowing us to extract more energy, processed foods do not keep us fuller for quite as long. Digesting fibre, protein, starch, and even natural sugars bound up in whole foods takes work and time. However, ultra-processed, pre-digested foods reduce this ‘extra work’, which means all of that food floods your bloodstream at once and dissipates as quickly as it enters. The rapid hit of energy provides an immediate dopamine spike but leaves us feeling hungrier again sooner.
For example, protein powders, or products like shakes and bars made from them, are effectively pre-digested, and your body needs less energy to digest and use them. While this might sound good, protein powders and supplements cause less dietary-induced thermogenesis and provide less long-term satiety than whole-food protein sources. Overall, amino acids from processed protein products create less long-term satiety than a whole-food protein source that your body has to work a bit harder to digest.
To put things into perspective numerically, only about 20% of the calories from processed protein powders are likely to be lost in processing. In contrast, this may be more like 35% of calories from minimally-processed whole-food protein sources. Whole food protein sources are always more satiating than refined protein sources.
But if you recall, protein isn’t the only macronutrient with thermogenic effects. Refined grains and sugars might provide only 5% DIT, whereas a whole-food carbohydrate source might have a DIT of 15% because it requires more digestion.
When it comes to fats, only 3% of total calorie value might be lost to thermogenesis in refined sources, whereas up to 15% may be lost in whole-food sources.
While the numbers are hard to quantify precisely, the bottom line is that the complete matrix of macronutrients bound together in minimally processed whole foods require much more digestion and are thus less efficient energy sources. While that would be bad news if you were a starving caveman, more losses create more heat which keeps us warm, and it also keeps us from absorbing and storing every extra calorie on our waistline.
Ultra-processed foods that are mostly a combination of added sugars, refined grains, and industrial seed oils are absorbed efficiently and require minimal effort for our bodies to digest. Thus, they hit our bloodstream quickly and leave us feeling hungry again shortly after because they assimilate into our bodies rapidly.
Calorie for calorie, we will absorb more of what we consume from ultra-processed foods and waste less digesting them.
Bottom line: the more processed a food is, the easier it is to digest, the lower the dietary-induced thermogenesis, the lower the satiety value, and thus the more we eat and absorb.
We Eat More Ultra-Processed Foods
Even when foods have similar macronutrient profiles, we seem to eat more ultra-processed foods.
In their 2019 study, Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake, Kevin Hall and colleagues found that subjects eat more and gain more body fat when they opt for ultra-processed foods. In contrast, they ate less and lost more weight with minimally processed foods.
We Expend Less Energy When We Consume Fat+Carb Ultra-processed Foods
While you might think we would feel more energetic if we consumed and absorbed more energy. But it appears the reverse is true!
Due to a mechanism known as the Randle Cycle, it appears that our bodies downregulate energy expenditure when we have a similar mix of energy from fat and carbohydrates coming in at the same time. If you’re eager, you can dive into the biochemistry of this process here.
Before the creation of processed foods, the fat+carb combo was rare and usually available only in autumn to help animals prepare for winter. So, it’s logical that this food might make us want to eat more of them and use less energy so we can fatten up to survive winter when food is scarce. It’s early days, but some research indicates that a highly processed diet decreases non-exercise activity thermogenesis in mice and humans.
Fats and protein were readily available throughout the winter, protein and fibre were ample during the spring, and summer provided protein and carbs. However, only in autumn were the weight-gaining, hunger-driving, hyper-palatable fat-and-carb combo foods available to enable us to ‘fatten up’ to survive the coming winter.
For more on eating with the seasons, see Escaping Our Infinite Autumn.
Why Are Ultra-Processed Foods Bad for Us?
As we mentioned before, ultra-processed foods combine refined fats, added sugars, and refined grains. This diabolical, hyper-palatable combination is often low in protein, making it poorly satiating and easy to overconsume. Additionally, it works on our dopaminergic system, eliciting our reward system and telling us to eat more, more, more! And we may even end up expending less energy when we consume carb+fat combo foods.
The table below shows the results of a multivariate linear regression of 141,171 days of data from people who have used Nutrient Optimiser when we consider the various energy sources in our diet. Consuming foods that contain more saturated fat, monounsaturated fat, starch and sugar all align with consuming more energy.
|Saturated Fat (g)||20.2||62.3||286||15.9%|
|Monosaturated Fat (g)||14.7||52.1||237||13.2%|
Moving from a low to a high saturated fat intake aligns with a 16% increase in calories consumed. Likewise, consuming more monounsaturated fat, starch, and sugar aligns with 13%, 11%, and 7% increases in energy, respectively.
While we need enough calories from our food to fuel our activity, ultra-processed foods tend to combine multiple sources of energy in the same food in ways that nature could never provide. The ingredients of the Oreo shown below are a great example of ultra-processed foods.
However, pretty much every packaged food you will find in the aisles of your supermarket follows the same formula: flour + seed oil + sugar + flavours + colours.
How Do We Define Ultra-Processed Foods?
Defining ‘ultra-processed foods’ is where things get interesting.
The generally accepted definition of ultra-processed foods contains many added ingredients and has been highly manipulated via multiple processes, like extrusion, moulding, milling, heating, and preservation.
The most recognised way to classify ultra-processed foods is the NOVA system, which has four categories:
- unprocessed or minimally processed foods,
- processed culinary ingredients,
- processed foods, and
- ultra-processed foods.
The NOVA classification was initially defined in a 2019 paper by Carlos A Monteiro et al., Ultra-processed foods: what they are and how to identify them, which states:
Processes enabling the manufacture of ultra-processed foods include fractioning whole foods into substances, chemical modifications of these substances, assembly of unmodified and modified food substances, frequent use of cosmetic additives, and sophisticated packaging.
Processes and ingredients used to manufacture ultra-processed foods are designed to create highly profitable (low-cost ingredients, long shelf-life, emphatic branding), convenient (ready-to-consume), hyper-palatable products liable to displace all other NOVA food groups, notably unprocessed or minimally processed foods.
A practical way to identify an ultra-processed product is to check to see if its list of ingredients contains at least one item characteristic of the NOVA ultra-processed food group, which is to say, either food substances never or rarely used in kitchens (such as high-fructose corn syrup, hydrogenated or interesterified oils, and hydrolysed proteins), or classes of additives designed to make the final product palatable or more appealing (such as flavours, flavour enhancers, colours, emulsifiers, emulsifying salts, sweeteners, thickeners, and anti-foaming, bulking, carbonating, foaming, gelling and glazing agents).
However, a 2022 paper, Ultra-processed foods: how functional is the NOVA system?, highlighted how the descriptive criteria used by NOVA still leave much room for interpretation and judgement.
Furthermore, history shows that food manufacturers cunningly manipulate ingredient lists to negotiate such food ranking systems.
So, is there a better way to classify ultra-processed foods that we should avoid?
How Can You Tell If a Food Is Ultra-Processed?
Rather than simply classifying ultra-processed foods by what they contain, we can also consider what they lack and their impact on satiety and how likely we are to overeat them.
As a general rule, ultra-processed foods are low in protein and fibre.
Protein is the most expensive macronutrient. It also provides the highest satiety, which means we eat less. This hurts the bottom line of food manufacturers because consumers don’t need to eat as much of their high-profit margin foods.
More processed foods tend to have their fibre removed to improve shelf life, whereas foods that naturally contain more fibre tend to be less processed. High-fibre foods are also digested more slowly and help us feel fuller for longer. Lastly, we don’t absorb as much energy per calorie in foods that still contain fibre.
Multivariate regression analysis shows that we consume 35% fewer calories when moving from a lower to a higher protein %, and 8% fewer calories when we consume foods with more fibre per calorie.
|Fibre (g/2000 cal)||11||44||124||-8.3%|
While protein and fibre are well-known for helping us feel satiated, other vital nutrients also contribute. Thus, protein and fibre are part of a complex of other beneficial essential nutrients that tend to accompany one another when found in whole food.
When we consider all essential vitamins, minerals, essential fatty acids, and amino acids, we see that a wide range of nutrients aligns with greater satiety. Along with protein, core macrominerals, like potassium, sodium, and calcium, also play an important role in feeling full. We need enough of these essential nutrients and keep eating until we get enough of them.
|Pantothenic Acid (B5)||4||15||-18||-1.1%|
The next table below shows the results of our multivariate analysis if we consider the nutrients that help us eat less and the energy sources that drive us to eat more together.
In this version of the multivariate analysis, the impacts of protein and fibre are redistributed to other essential nutrients that align with eating more, like monounsaturated fat and starch, shown towards the bottom of the table.
Using this multivariate regression analysis, we can rank foods based on the number of calories we’ve forecasted someone will consume of them based on their nutrient profile.
This allows us to prioritise foods that contain the nutrients that increase satiety while avoiding fat-and-carb combo foods that often lead to lower satiety outcomes. Our satiety index score and nutrient density rankings also are very effective in helping us identify ultra-processed foods and those that will provide the nutrients we need and greater satiety.
Is Fortification Good for Us?
Interestingly, many ultra-processed foods contain fortified nutrients, which allows them to brag that they are good sources of nutrients X, Y and Z on the package.
However, while supplemental and fortification nutrients may be beneficial if we have a deficiency, they may not be great for our waistline. In his book, the End of Craving, Mark Schatzker draws attention to experiments in the 1960s where pig farmers realised they could grow pork more quickly without their livestock getting sick by keeping them indoors and feeding the diet high in corn fortified with B vitamins. As a result, the pigs would chow down on more fortified grains and achieve unprecedented growth rates.
Shortly after this discovery, food manufacturers ramped up the fortification of breakfast cereals and other processed foods for humans. While this might look like a great advance for public health, it may also simply satisfy our subtle cravings for these nutrients that are not naturally contained in ultra-processed foods. Thus, we are less likely to get bored of eating these foods and go in search of the meat, seafood and veggies that naturally contain these nutrients.
I highly recommend Mark’s books, The Dorito Effect and The End of Craving, to learn more. You can also listen to us chat about this here.
Additionally, Mark also highlights a range of experiments that suggest we tend to eat more when the nutrients and energy our food provides don’t align with their taste and texture. Our bodies sense something awry in our food environment and eat just a little more to account for the unknown risk. There is still much to learn in this area. In the meantime, the safest approach is to ensure the food you eat tastes terrific simply because it contains the nutrients your body needs.
What Are the Most Processed Foods to Avoid?
The first step to avoiding processed foods is to review the ingredients list and keep an eye out for anything that includes sugar, refined flour, and seed oils.
Flavours, artificial sweeteners, fortified nutrients, or anything you can’t picture or wouldn’t want to eat all by itself listed (i.e., titanium dioxide) are also dead giveaways that the raw ingredients are ultra-processed and likely provide minimal nutritional value!
The chart below shows how several popular foods stack up in terms of satiety index score vs nutrient density (per serving). We can see that foods like Mars Bars, Kit Kats, corn chips, brownies and Hershey’s kisses are plotted towards the bottom left. These are the poorly satiating foods you want to avoid. You can dive into the detail in the interactive Tableau version of this chart here.
How Can You Develop the Habit of Avoiding Processed Foods?
Rather than simply avoiding ‘bad’ things in food, we find it more useful to prioritise foods that provide the greatest satiety and nutrient density.
To help you do this, the chart below shows a wide range of popular foods plotted on the landscape of satiety index vs nutrient density (per serving). The colour scheme is based on nutrient density (per calorie). You can dive into the details in the interactive Tabluea version of this chart here.
- You should choose foods towards the right if you’re trying to feel full with fewer calories.
- You should prioritise foods towards the top if you want to get more nutrients from foods that make up the foundation of your diet.
- If you want to get more nutrients per calorie and greater satiety, avoid foods in red and prioritise the ones in green.
We can also do this with recipes to identify those that will help us feel more satiated and provide more of the nutrients we need to thrive. The chart below shows our 850 NutriBooster recipes on the diet quality score vs protein % landscape. The colouring is based on our satiety index score. If you want to dive into the detail, click here to view the interactive version of this chart in Tableau.
- Ultra-processed foods combine refined ingredients like added sugar, refined grains, and industrial seed oils with flavourings and colourings to create low-satiety, energy-dense, palatable, nutrient-poor, high-profit foods that we desire and want to buy more of.
- These foods provide us with rapidly absorbable energy from fat and non-fibre carbohydrates that hit our bloodstream quickly. As a result, our blood sugar spikes and crashes, leaving us hungry again when it comes crashing down not long after. While the volume of these foods might have us feeling full initially, they lack protein, fibre, minerals, and vitamins that elicit a feeling of long-term satiety.
- Ultra-processed foods simultaneously fill your body’s glucose and fat fuel tanks in a way that is rare in nature. This provides a supraphysiological dopamine response that drives us to want more of them.
- Ultra-processed foods typically contain a long list of ingredients, including flavours that make them hyper-palatable, colourings to make them look nutritious, and a smattering of synthetic nutrients that keep us from getting bored of eating them.
- By quantifying the unique characteristics of ultra-processed foods that we tend to overeat, we can reverse-engineer the problem to ensure we avoid them wherever they may be hiding.