Food Sick

Food Sick: How Processed Foods Fueled the Metabolic Health Crisis

10 minutes read

Worldwide obesity has nearly tripled since 1975, and more than 90% of Americans are metabolically unhealthy — processed foods are one of the major forces driving this health decline [1].

Processed foods are products of Big Food, which is working to produce shelf-stable, cheap, and highly-palatable foods that keep consumers craving more. You may not even be aware of where some of these ingredients are hidden and the science behind why they are so tasty.

Processed foods vs. ultra-processed foods

The term “processed foods,” as we use it here, refers to highly manipulated shelf-stable snacks, ready-made foods, and beverages that have additives such as sugar, salt, fat, and colorings. 

Some people refer to these foods as “ultra-processed foods” (UPFs). The term “ultra-processed food” was created by a food classification system, NOVA, that categorizes foods based on the degree of food processing (i.e., the “physical, biological, and chemical techniques used after foods are separated from nature, and before they are consumed or else made into dishes and meals”) rather than their nutritional value [2, 3].

The food processing that we need to be conscious of is when high amounts of sugar, fat, salt, and artificial coloring are added to foods — not just ice cream, chips, and other obvious “junk foods,” but staples such as breakfast cereal, fruit gummies, bread, oat milk, dehydrated/microwavable meals, and more [4].

When these day-to-day packaged items undergo a significant amount of processing and engineering to have long shelf lives and palatability, individuals can quickly consume more than their daily recommended intake of sugar without even knowing it [2]. Studies have shown that a high intake of these products contributes to obesity and cardiometabolic risk factors in children and adults [4]. 

An overview of the processed food industry

The consumption of processed food has been on a steady incline over the past two decades in the United States — as a result, overall diet quality has decreased while chronic disease rates rise [5]. 

In a 2022 study, researchers found that processed food consumption in U.S. adults had increased from 53.5% to 57.0% from 2001-2018. This means that over half of the US diet comes from processed foods.

Grocery stores play a key role in consumer dietary habits. GroceryDB, a database that calculated the degree of processing for over 50,000 food items sold in Walmart, Target, and Whole Foods, found that a staggering 73% of the US food supply is ultra-processed, and on average these foods are 52% cheaper than minimally-processed food alternatives [7].

The implications of these results are extraordinary. Not only are UPFs more readily available to the average consumer, but they’re also cheaper than their whole-food, unprocessed counterparts. In other words, it’s cheaper — and easier — to eat unhealthy food.

How processed foods are designed to be addictive

The food industry is responsible for creating misguided notions about health and wellness. More specifically, Big Food has carefully created convenient, packaged options that have bliss points, palatability, and vanishing caloric density to hook consumers. 

Bliss points

Humans have had an evolving relationship with salt, sugar, and fat.

Our modern-day abundance of these three ingredients — and an ever-growing number of ways to manipulate them in packaged foods — have pushed the boundaries for food production and raised consumers’ expectations and satisfaction levels.

Big Food aims to produce a state of satiety and pleasure where the levels of saltiness, sweetness, and richness (i.e., salt, sugar, and fat) are perceived by the consumer as just right [8].

Food has become a science experiment to see which ingredients stimulate our senses the most and give us the most pleasure when we eat them. Ingredients are manipulated in numerous combinations until finding an optimal formula that achieves the industry’s bliss point. Food engineers analyze a mathematical model that maps out ingredients according to sensory perceptions that these ingredients create [9]. 

Today, craveable foods, such as crunchy cereals, cookies, fried foods, and soft drinks, drive overeating and have a detrimental impact on people’s health worldwide.


Our brains are hardwired to love sugar, as it is both highly palatable and rewarding.

However, excessive sugar consumption targets our brains’ reward system and will essentially “turn off” our ability to recognize that we are full and to stop eating [10]. 

Palatability refers to foods high in salt, sugar, and fat content, which target our brain’s evolutionary desire for these types of foods.

Since the 1970s, high fructose corn syrup has been an attractive additive for manufacturers to include in their products due to its cheapness and sweetness level. Food products that contain additives like high-fructose corn syrup are highly palatable. Our brain creates a pleasure response to eating sugar by releasing dopamine. 

Foods with high palatability induce an addiction-like deficit in the brain’s reward function [11]. The brain won’t be satisfied or happy until it gets what it wants: more sugar.

Overconsumption of highly palatable foods can be compared to drug addiction because these foods generate continuing increases in food intake that lead to sources of motivation that drive overeating.  

Vanishing caloric density

Vanishing caloric density refers to certain foods like ice cream, popcorn, etc., that trick your brain into thinking it lacks calories. These foods typically melt down quickly while you eat them.

For example, when you eat Cheeto puffs, they essentially melt in your mouth. This melting tells your brain there are no calories in them and makes you think you can eat them forever. Foods that quickly “vanish” in your mouth are more rewarding to the brain, reduce gastric satiety, and encourage overconsumption [12]. It’s pleasure without satiety. 

Energy density

Energy, or caloric density, refers to the number of calories each gram of a food item contains [12]. Processed foods like donuts, chips, and cookies all have high energy density.

Humans evolved in a low energy-density environment. However, with the new discoveries of food additives and technology, increasing the energy density (i.e. increasing the amount of salt, sugar, and fat) in food makes it taste saltier, sweeter, and richer.

Research shows that despite our evolutionary upbringing, we prefer high energy density foods to low. Brain scans show a reduced pleasure response when subjects view a plate of vegetables versus a higher-calorie alternative [12].    

How processed foods affect our health: a landmark study

In 2019, a randomized controlled trial examined the effects of ultra-processed foods in 20 inpatient adult volunteers for the first time, revealing major implications on body weight changes, eating rate, and metabolic health at large [13].

Volunteers were randomly assigned to either the ultra-processed or unprocessed diet for two weeks followed immediately by the other diet for the final two weeks. The meals were matched across diets for total calories, energy density, macronutrients, fiber, sugars, and sodium, but differed in the percentage of calories.

Scientists learned the following general takeaways from the study:

  • The increased availability and consumption of processed foods are associated with rising rates of obesity and Type 2 diabetes. 
  • Processed foods facilitate overeating and the development of obesity due to being high in calories, salt, sugar, and fat and are engineered to trigger abnormal appetite resulting in compulsive eating behavior.
  • Processed foods may disrupt the communication between the gut and the brain (known as the gut-brain axis), which influences an increase in food reinforcement and overall intake of calories.

But they also uncovered additional data that presented astonishing insights around eating rate and metabolic health.

Eating rate and body weight changes

In other words, there was a faster eating rate for UPFs that led to overconsumption of calories, sometimes by an additional 25% for individuals. This was accompanied by a weight gain of around 0.9 kilograms or 2 pounds. Conversely, eating an unprocessed diet resulted in weight loss of an equivalent amount [13]. 

The results echo the tactics we’ve described regarding Big Food’s intentional manipulation of foods using bliss point, palatability, and vanishing caloric density to encourage you to overeat — all the while not even knowing that you’re consuming more calories than you’d like and gaining your weight. 


The study also revealed the impact of processed foods on our hunger hormones and satiety levels. In the unprocessed diet condition, the appetite-suppressing hormone PYY increased compared to the ultra-processed diet and baseline [13]. 

Additionally, ghrelin, the hunger hormone, was decreased during the unprocessed diet compared to baseline. This means that hunger signals were lowered when eating a diet that did not contain processed foods. In other words, participants felt more satisfied and full after eating a diet with whole foods in their natural state.

Before this study, there was no way to imply a causal relationship between diets high in processed foods and health problems. Now, we know that processed foods cause people to unconsciously eat too many calories and gain weight [13].

Cognitive decline  

Other studies have found that consumption of UPFs can lead to cognitive decline — with faster decline among people who eat more UPFs. In a 10-year study published in 2022, researchers organized Brazilian individuals aged 35-74 years old into four groups according to how much ultra-processed foods they ate [14].

They found that participants in the three groups with the highest UPF consumption showed a 28% faster rate of cognitive decline and a 25% faster rate of executive function decline compared to participants in the group with the lowest UPF consumption.

Avoiding processed foods in your diet

Now that you’re aware of the facts and health effects, you can make educated decisions about what’s on your plate or in your grocery cart.

As ubiquitous as processed foods are, there are plenty of strategies for avoiding them. Here are some suggestions on how to avoid processed foods in your diet, if you choose to:

  1. Stick to shopping around the edges of the grocery store. This is where fresh produce is often located, rather than the middle aisles which are where the processed foods live. Try to make your cart and your plate as colorful as possible by incorporating more fruits and vegetables
  2. Read ingredient labels carefully. Companies will try to trick you by including labels that state “gluten-free, keto, etc.,”  to make the product sounds “healthier” than it is. 
  3. Keep in mind these healthy swaps for common processed foods:
  • Instead of fruit gummies, try dried fruit.
  • Instead of breakfast cereal, try homemade granola (lightly sweetened with honey or maple syrup instead of sugar).
  • Instead of chips, try air-popped popcorn.
  • Instead of pre-packaged microwaveable meals, prep dinners in bulk and freeze.

Key Takeaways

It can be overwhelming to learn how Big Food has evolved over the years and the impact that it has on our health. However, now you have the knowledge you need to make empowered choices for your health benefit. 

  • Through food additive discovery and new technologies, the food industry has been able to produce processed foods that keep you wanting more.
  • Processed foods are designed to be addictive. They target your brain’s reward system and trick you into thinking there are no calories being consumed as they melt in your mouth.
  • A new study found that consumption of a diet high in processed foods has been directly associated with weight gain and increased calorie intake. 
  • There are many ways to avoid processed foods during your next trip to the grocery store. You have the ability to make better choices now being aware of what processed foods entail.



Written by: Peyton Lessard, MS
Reviewed by: Emily Johnson, MSc RD

Table of Contents

  • Processed foods vs. ultra-processed foods
  • An overview of the processed food industry
  • How processed foods are designed to be addictive
  • How processed foods affect our health: a landmark study
  • Avoiding processed foods in your diet
  • Key Takeaways


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