In January of this year, the USDA updated their dietary guidelines for Americans. Despite the political and scientific controversy surrounding many of the new recommendations, the focus on discouraging processed foods was widely celebrated by people across the political divide and by many public health advocates. Ultra processed foods (UPF) can be affordable, good tasting, convenient, have long shelf lives…and profitable for food companies. They can also hijack the ancient wiring of our brains and encourage people to eat calorie-dense and nutrient-low foods that lead to health problems like obesity. But what about them makes them so appealing to consumers?
A Brief History of Food Processing
Whether it’s pressing olives for oil or fermenting grains or milk for beer or yogurt, since ancient times people have been processing foods. In the 20th century improvements in science and the necessity of war accelerated the advancement of modern processed foods.
- The World Wars and Food Innovation: War was the single biggest catalyst for food processing. The military needed food that was lightweight, calorie-dense, and could last in the uncertain conditions of war. Technologies developed for the front lines like dehydration, canning, and freeze-drying moved into the civilian kitchen after the wars ended. Interestingly, M&M’s were invented for the military during this period, because their outer crispy shell was less likely to melt than normal chocolate bars.
- Space Age Food: Post-WWII America saw a boom in the middle class and a shift in gender roles. This era saw the birth of modern food chemistry. Scientists began using additives to ensure that processed food tasted the same every time, regardless of when it was made. In 1953, Swanson introduced the TV Dinner. To promote products like TV Dinners, convenience and freedom from the kitchen were marketed, especially to women. The message was the family was moving from the dinner table to the living room.
- The Age of Ultra Processed Foods: Starting in the 1970s and continuing into the 1980s advances in food science led to what has become today’s UPF’s. In the early 70s, Japanese researchers perfected a way to turn corn into a liquid sugar that was cheaper and sweeter than cane sugar. Then, In 1977, the first dietary recommendations for the U.S. recommended cutting fat. The food industry responded by creating thousands of “low-fat” or “light” products. To make these low-fat products palatable, producers turned to ingredients like the recently created and inexpensive high fructose corn syrup and other chemical flavor enhancers.
Types of Processed Foods
All processed foods are not the same and are classified by their level of processing.
- Unprocessed or Minimally Processed: Natural foods altered by removal of inedible parts, drying, crushing, boiling, or freezing. No substances (salt, sugar, oil) are added.
- Processed Culinary Ingredients: Substances obtained directly from unprocessed or minimally processed foods by processes like pressing, refining, or grinding. They are used to season and cook unprocessed or minimally processed foods.
- Processed Foods: These are made by adding salt, sugar, or oil to minimally processed foods. They usually have 2–3 ingredients and can be made in a home kitchen.
- Ultra Processed Foods: These are foods that have undergone intense processes, such as refining, high-temperature extrusion, or molding. They typically include colors, flavorings, emulsifiers, and other artificial ingredients.
The Science of the Desirability of Food
Now that we have looked at the background of processed foods, we can shift to the fundamental nature of why these foods are so appealing to the brain and body. The human drive for food is designed for survival. Before there was a McDonalds or DoorDash and all food was whole foods, the brain rewarded people that ate foods high in fat and sugar. When you weren’t sure when or where your next meal came from, eating calorie-dense meat or fruits meant a better chance of living and reproducing. To do this, the body developed a reward system. When a person eats foods high in fat or sugar the brain releases the neurotransmitter dopamine. Dopamine is a crucial neurotransmitter and chemical messenger in the brain that regulates motivation, reward anticipation, motor control, and cognitive functions like memory and attention. It drives the “wanting” or craving aspect of pleasure, prompting action toward goals, and is essential for movement, mood regulation, and learning.
How Food Science Hijacked the Human Brain
UPF’s often contain combinations of ingredients that are not found in nature. Meat is high in fat, but is not high in sugar. Fruits are high in sugar, but are not high in fat. The combination of the two nutrients needed for human function makes the brain identify something that is highly desirable, thus good tasting and pleasurable to eat. With modern science, these good tasting ingredients can be amplified and can encourage overconsumption. Here are some of the reasons how and why:
- The Bliss Point: Food scientists use data to find the “bliss point” or the precise ratio of salt, sugar and fat that maximizes pleasure without overwhelming the palate. Since in nature you rarely find high fat and high sugar together, UPFs like donuts or flavored chips combine these in a way that provides an intense sensory hit, making the brain crave more immediately.
- Dopamine and the Reward System: When you eat UPF’s, your brain releases a surge of dopamine in the nucleus accumbens (the same area activated by nicotine or cocaine). Because these foods are highly refined, they hit the bloodstream almost instantly. Over time, the brain may downregulate its dopamine receptors to protect itself from overstimulation. This means you need to eat more of the food just to feel the same level of pleasure.
- Vanishing Caloric Density: Many UPF’s are engineered to have vanishing caloric density. This describes foods that melt in your mouth quickly. This “melting” signals to the brain that you aren’t actually eating that many calories, even if you are. Your stomach and brain don’t register that you are satiated, leading to overeating.
- Lack of Fiber and Protein: Natural satiety (feeling full) is triggered by fiber, protein and the physical volume of food stretching the stomach. Ultra-processing usually removes fiber and water to increase shelf life. Without fiber to slow down digestion, you experience a rapid blood sugar spike followed by a crash. That crash triggers a hunger signal, even if you already consumed a lot of calories.
- Texture and Mouthfeel: The physical experience of eating UPF’s is often highly curated by food science. Unlike a steak or a salad, which requires significant chewing, UPFs are often soft and easy to swallow. The faster you can eat, the less time your gut has to send “I’m full” hormones to your brain.
In total, UPF’s are designed to be visually appealing, cheap, have a long shelf life and be good tasting, but often with little regard for their nutritional value. UPF’s are often high in sugar and or fat, high in sodium and can contain additives known to be bad for health. This combination promotes over consumption and helps contribute to non-communicable diet related diseases like obesity, diabetes, heart disease and some cancers. UPF’s hack our ancient wiring for pleasure and become addictive to many people. How we address this will determine a lot about the future of American health.
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