Viewing food as a system of biological signals helps explain why diets affect people differently and how nutrition can better support metabolism, mental health, and long-term well-being.
Modern nutrition science has continued to see food through numbers. Calories, macronutrients, ingredient lists, and percent daily values have become the primary language of eating. This approach, often referred to as “nutritionism,” assumes that the effects of the food we consume can be understood by breaking it down into isolated components and optimizing those components. If the label looks right, the thinking goes, good health should follow.
But human experience tells a different story. Food is not just fuel; it is not merely a list of nutrients. Meals carry aroma, texture, memory, and meaning. Cultural traditions shape how foods are prepared, combined, and shared. Emotional states influence appetite and response. These elements are not superfluous add-ons to dietary health; they are part of how the body interprets what we eat.
Increasingly, modern science supports this lived reality. Foods that appear equivalent based on nutrition labels can produce very different outcomes depending on when we eat, as well as the structure, content, context, and prior exposure. The body does not simply absorb nutrients; it responds to patterns of signals shaped by experience and environment.
From this perspective, food does not simply function as fuel or as random nutrients, but as information—signals that biological systems interpret and respond to. It communicates simultaneously with metabolism, hormones, microbes, and behavior. Health does not emerge from perfect labels or isolated nutrients, but from the relationships between how these signals are organized over time. Moving beyond nutritionism does not abandon science—it strengthens it by aligning prevailing models of nutrition—such as calorie-based energy balance and nutrient reductionism, with how living organisms actually exist as complex adaptive systems.
Modern nutrition’s fascination with numbers did not begin with health. It began with economics.
In the 19th century, scientists studying industrial steam engines sought a way to identify the most economically efficient fuel, which led to the concept of the calorie emerging as a unit of heat energy. French chemist Nicolas Clément first described the calorie in the early 1800s as a measure of heat, a tool for understanding why coal-powered engines were more economically efficient than earlier wood-powered versions in driving the steam engine that powered the Industrial Revolution.
It was the American agricultural chemist Wilbur Olin Atwater who introduced the concept of calories into the field that would later become human nutrition. His goal, however, was not just scientific curiosity but was closely tied to a practical economic question facing the rapidly industrializing United States. Although the Industrial Revolution had taken strong hold in America, much work was still performed by people and animals. The question remained: how could workers, soldiers, laborers, and animals be fed to maximize work output at the lowest economic cost?
In effect, Atwater treated the human body as a biological engine, and food became the fuel. The problem was framed as one of energy input and mechanical output. Much as engineers sought the most efficient coal for steam engines, Atwater and his colleagues began asking which foods provided the most energy for the lowest cost.
Within that framework, the calorie was an extraordinarily powerful tool. It helped governments design rations, guide agricultural policy, and combat undernutrition. But once food was defined primarily as fuel and humans as biological steam engines, science increasingly focused on measuring energy.
However, energy balance, viewed in isolation, failed to explain certain widespread diseases of the time, such as beriberi. The discovery of vitamins in the early 20th century revealed that food contained additional biologically essential components beyond calories. In response, the caloric model expanded into what critics later called nutritionism—the idea that foods can be understood primarily by breaking them down into their component nutrients. Calories, proteins, fats, carbohydrates, vitamins, and minerals became the dominant metrics in dietary science. If the individual parts could be measured and optimized, the thinking went, good health would follow.
This approach proved remarkably successful in addressing diseases of deficiency, such as identifying that vitamin C eliminated scurvy. Vitamin B1 cured beriberi, and Vitamin D reduced rickets. By isolating the specific nutrients responsible for these conditions, scientists designed targeted public health interventions that dramatically improved population health.
Yet the success of nutritionism also reinforced a powerful assumption: that understanding food could be reduced to the sum of its parts.
By the mid- to late 20th century, however, a new challenge emerged. The dominant health problems of modern societies are no longer diseases of deficiency but diseases of excess, dysregulation, and environmental mismatch; diseases such as obesity, diabetes, cardiovascular disease, and metabolic disorders. These conditions proved far more difficult to explain solely in terms of nutrient components. Two foods with nearly identical nutrient profiles could elicit very different metabolic responses depending on how they are structured, processed, combined, and consumed.
Nutritionism gave scientists powerful tools for measuring food, but it also narrowed the questions being asked. When food is framed as fuel, the central problem becomes an exercise of thermodynamic bookkeeping. When it is reduced to its nutrient components, the issue is optimizing the disconnected biochemical components.
But living organisms do not experience food as isolated nutrients or abstract calories. Meals are a part of their daily environmental experience—patterns of signals interacting with metabolism, microbes, hormones, and behavior over time.
Understanding those signals requires a different way of thinking about food.
For much of the 20th century, nutrition science treated nutrients primarily as chemical building blocks. Proteins supplied amino acids for tissue growth, fats stored energy, and formed cellular membranes; carbohydrates fueled metabolism; and vitamins and minerals served as cofactors in biochemical reactions. Within this framework, the central question was how much of each component the body required to function properly.
Over time, however, it was discovered that nutrients do not merely supply raw materials; they also act as biological signals that help regulate the body’s internal systems.
Macronutrients help coordinate energy balance and metabolism through signaling pathways, including insulin and other hormonal responses. Micronutrients function as regulatory molecules that influence immune activity, enzymatic processes, and gene expression. In both cases, nutrients shape how biological systems respond to the environment rather than just supplying chemical building blocks.
Each meal initiates a coordinated cascade of biological signals, including nervous system communication via vagal afferents and enteroendocrine cells, hormones such as insulin, glucagon, ghrelin, and leptin, and short-chain fatty acids from our gut microbiome. The body is therefore constantly interpreting a vast array of dietary inputs and adjusting its internal physiology in response.
These discoveries gradually expanded the scientific understanding of diet. Food does not just provide energy and nutrients; it also influences regulatory networks that shape metabolism, immunity, and behavior.
Yet even this signaling perspective remains incomplete. Nutrients rarely act in isolation. They are packaged in foods that contain thousands of interacting compounds, structured as part of meals in ways that can produce distinct physiological responses. Current estimates suggest that the foods humans consume contain roughly 140,000 identifiable chemical compounds.
Once ingested, signals are simultaneously interpreted by multiple biological systems, and each meal occurs within social and environmental contexts that add further layers of meaning.
The digestive, endocrine, immune, and nervous systems all participate in this process. Signals generated by food influence the gut microbiome, microbial metabolites influence the brain, and hormonal pathways connect metabolic responses with behavior and mood. What was first described as a simple act of “fueling up”—eating a meal—is in fact a complex biological conversation occurring across multiple layers of physiology.
Understanding diet, therefore, requires moving beyond viewing nutrients as isolated chemical inputs. Instead, food should be understood as part of a broader network of biological communication, in which dietary signals are interpreted across interacting systems.
It is within these interconnected networks that the deeper informational nature of food begins to emerge.
One of the clearest examples of biological communication occurs along the gut-brain axis, the network that links the digestive system, nervous system, and the trillions of microbes living in the human intestine. Far from functioning independently, these systems continuously exchange signals, forming a dynamic bidirectional communication loop that influences metabolism, immunity, mood, and cognition.
The gut microbiome plays a central role in this dialogue. Microbes in the intestine metabolize components of the foods we eat, producing biologically active molecules that interact with the host. Among the most studied are short-chain fatty acids such as acetate, propionate, and butyrate, which influence immune function, inflammation, and neuronal signaling. Other microbial products affect neurotransmitter systems, stress responses, and metabolic regulation.
Communication between the gut and the brain occurs through several pathways simultaneously. The vagus nerve provides a direct neural connection between the digestive tract and the central nervous system—enteroendocrine cells lining the intestine release hormones that transmit information about nutrients and microbial metabolites. Immune signaling molecules convey information about the inflammatory state. Circulating microbial metabolites can also directly influence brain function. Through these multiple channels, gut signals can alter mood, cognition, and behavior.
Research over the past two decades has increasingly linked alterations in the gut microbiome with psychiatric conditions such as depression and anxiety. Individuals with these disorders often exhibit distinct microbial profiles compared with those of healthy populations. Experimental studies suggest that changing microbial communities can influence the host’s emotional and behavioral responses.
One of the most striking demonstrations of this relationship comes from fecal microbiota transplantation (FMT), a procedure in which microbial communities from a healthy donor are transferred to a recipient. Originally developed to treat severe Clostridioides difficile infections, FMT has revealed the remarkable influence microbial ecosystems can exert on host physiology. In experimental models, transplanting gut microbes from individuals with depression into germ-free mice can induce depressive-like behaviors in the recipient animals. Conversely, microbial communities from healthy donors can improve behavioral and metabolic outcomes, suggesting a causal relationship.
Researchers have also explored more modest interventions to reshape microbial communities. Certain probiotic strains—sometimes called psychobiotics—have shown potential to influence mood, stress responses, and cognitive function. Early clinical studies suggest that specific microbial formulations may reduce symptoms of anxiety and depression, although this field remains in its early stages.
These findings reveal that biological systems communicate through signals that can change form as they move across different functional layers of the body. Microbes may metabolize a dietary fiber molecule into short-chain fatty acids that influence intestinal cells, which, in turn, send neural and hormonal signals to the brain. At each step, the signal’s form changes, yet the underlying message persists.
In some ways, this process resembles downloading music. A singer’s voice begins as sound waves that are captured by a microphone and converted into digital data. That information travels across networks as pulses of light through fiber-optic cables, becomes electromagnetic signals in a router, and is finally transformed back into sound waves through a phone’s speaker. A person’s ear converts those vibrations into electrical impulses that the brain recognizes as a familiar song. The signal’s physical form changes repeatedly, yet the information remains the same. The song remains the same.
In the body, food undergoes a similar process of translation. Nutrients become microbial metabolites; metabolites trigger hormones and neural signals; those signals influence the brain and behavior. What began as a meal becomes a cascade of biological messages moving across multiple physiological systems.
Seen from this perspective, eating is not merely an act of fueling the body. It marks the beginning of an ongoing exchange of information linking diet, microbes, metabolism, and mental health.
For most of human history, food existed within relatively stable ecological and cultural systems. Meals consisted largely of minimally processed plants, animals, and fermented foods prepared using traditional techniques. These foods carried signals that biological systems had encountered for thousands of generations.
Over the past century, however, the structure of the food environment has changed dramatically. Increasingly, diets in industrialized societies are dominated by ultra-processed foods (UPFs): products formulated from refined ingredients, additives, flavor systems, and industrial processing methods designed to maximize shelf life, convenience, profit, and sensory appeal.
These foods are not “modern versions” of traditional ingredients. They are structurally different in ways that can alter how biological systems interpret them.
Ultra-processing breaks apart the natural matrix of whole foods, isolates specific compounds, and recombines them into novel formulations. Sugars, refined starches, fats, emulsifiers, and flavor enhancers are often added in proportions rarely encountered in natural foods. The result can be products with intense sensory properties such as sweetness, saltiness, creaminess, and crunch. But these sensory signals in UPFs are often only loosely connected to their corresponding biological signal. A zero-calorie artificially sweetened beverage signals sweetness to the brain and digestive system, yet the expected metabolic payload never arrives.
This separation between sensory signals and physiological outcomes may matter more than previously recognized.
In traditional foods, taste, texture, and nutrient content evolved together. Sweetness tended to signal energy. Bitterness often signaled potentially harmful compounds. Texture and fiber influenced digestion and satiety. Over time, biological systems learned to interpret these cues.
Ultra-processed foods can disrupt this relationship. Intense flavors signal nutrients that are not present, while rapidly absorbed carbohydrates or fats may arrive in the body faster than expected. Additives that modify texture, stability, or shelf life may further alter how food interacts with the gut environment, distorting the original biological message.
Research increasingly links diets high in ultra-processed foods with obesity, metabolic disease, cardiovascular conditions, and other chronic illnesses. Across large population studies, higher consumption of UPFs consistently correlates with poorer health outcomes, showing a clear dose-response relationship: as the proportion of ultra-processed food in the diet increases, health risks rise in parallel. In several cohorts, each incremental increase in ultra-processed food consumption corresponds with progressively higher cardiometabolic risk.
Critics sometimes note that such findings are observational, but similar patterns once characterized early research linking cigarette smoking to lung cancer. Over time, accumulating evidence from multiple lines of inquiry strengthened the case for causation. A similar convergence is now emerging regarding UPFs.
In light of these findings, a deeper question arises. How do such food signals become unreliable?
One possibility is that UPFs introduce noise or errors into dietary messages. The result is signals that our biological system struggles to interpret accurately. When taste, texture, nutrient delivery, and microbial responses no longer align in familiar ways, the regulatory networks that govern appetite, metabolism, and satiety may have greater difficulty maintaining balance. That opens the door for metabolic errors and downstream effects like obesity, type 2 diabetes, and cardiovascular disease.
This does not mean that individual foods are inherently “good” or “bad.” Rather, it suggests that the structure and informational content of food may matter as much, if not more, than the nutrients.
Understanding how modern diets influence health, therefore, requires more than counting calories or measuring isolated nutrients. It requires examining how foods interact with the body’s complex communication networks—and whether our body can understand the message.
If food functions as biological information, then designing healthier diets involves more than selecting the “right” nutrients. It requires understanding how dietary messages interact with the body’s regulatory systems over time.
Traditional nutrition advice often focuses on composition: how many calories, how much fat, how many carbohydrates. But from an informational perspective, diet is defined not only by what we eat but also by how signals are organized over time and across biological context.
Meal timing provides one clear example. Human metabolism follows circadian rhythms that influence insulin sensitivity, hormone secretion, digestive efficiency, and energy use throughout the day. Eating the same meal in the morning can produce very different metabolic responses than eating it late at night. Research in chrononutrition increasingly shows that aligning meals with circadian rhythms, such as concentrating food intake earlier in the day or allowing overnight fasting intervals, can improve metabolic regulation even when total calorie intake or nutrient content remains unchanged.
Stress physiology also intersects with dietary information. The hypothalamic-pituitary-adrenal (HPA) axis regulates the body’s response to environmental challenges, shaping metabolism, appetite, and immune responses. Chronic stress can alter microbial communities, disrupt metabolic signaling, and influence dietary choices, creating feedback loops between behavior and physiology.
Through the Food as Information lens, healthy dietary patterns emerge not by optimizing isolated nutrients but from coordinating multiple informational signals to produce a coherent message. The composition of foods, the structure of meals, the timing of eating, and the surrounding environment all influence how biological systems interpret dietary signals.
This perspective also helps explain why many traditional dietary patterns—from Mediterranean food cultures to East Asian meal structures—often support health despite wide variation in specific ingredients. These dietary traditions tend to organize meals around minimally processed foods, at regular intervals, and in socially structured eating environments, resulting in recognizable, familiar, and coherent biological messages.
Designing healthier diets, therefore, may depend less on a single optimal nutrient, for example, “Eat more protein,” and more on restoring informational patterns that biological systems recognize and respond to effectively.
If food functions as biological information, then changes in the food environment represent more than shifts in cuisine or convenience. They represent large-scale alterations in the informational landscape that human physiology interprets through diet.
Over the past half-century, global food systems have undergone profound transformation. Industrial processing, global supply chains, and large-scale food manufacturing have dramatically increased the availability of highly refined and ultra-processed products. In many high-income nations, these foods now account for more than half of total dietary intake.
This shift has occurred alongside a striking rise in chronic diseases such as obesity, type 2 diabetes, cardiovascular disease, and metabolic syndrome. While many factors contribute to these conditions, including sedentary behavior, aging populations, and socioeconomic changes, the transformation of the food environment has emerged as a central concern in the public health dialogue.
From a traditional nutritionism perspective, the problem has been framed as one of excess calories or unbalanced nutrients. But the Food as Information framework suggests a new paradigm. Modern food systems may be altering the patterns of dietary signals affecting human biology at a population scale.
When the majority of foods in the environment are industrially formulated, rapidly absorbed, and engineered for profit and purchase, the informational cues that once guided appetite regulation, biologic signaling, microbial ecology, and metabolic health may have become increasingly difficult for biological systems to interpret. The modern food environment, therefore, does not merely supply different nutrients; it presents an unfamiliar informational ecosystem.
Understanding diet in these terms opens new possibilities for public health. Rather than focusing exclusively on individual nutrient targets, dietary guidance may benefit from emphasizing patterns that restore recognizable biological messages: minimally processed foods, regular meal timing, a diversity of diets, and social environments that align more closely with the signals human physiology evolved to interpret.
Seen through this lens, improving population health may depend less on changing what individuals choose to eat and more on reshaping the informational structure of the food environment itself.
For more than a century, nutrition science has sought to understand food by measuring it. Calories, nutrients, and dietary components provided powerful tools for addressing deficiencies and guiding public health policy. Yet the dominant health challenges of the 21st century—obesity, metabolic disease, and chronic inflammation—have proven far more difficult to explain using these same reductionist models.
The emerging science reviewed here suggests that something deeper may be at work. Food does not simply deliver energy or nutrients. It carries information interpreted by intertwined biological systems. Health emerges not only from what we eat but also from how those dietary messages are structured, timed, and interpreted across these systems.
Living organisms are not simply the result of chemical equations. Complex chemistry occurs across the universe in many inanimate forms. Living organisms are complex adaptive systems that continually process information from their environments to maintain balance and survive. The meals we experience are among the most important informational inputs shaping that process.
Our modern food environment has altered the messages we—and the gut microbiome that co-evolved with us—receive in ways we are only beginning to understand. If we are to meet the diet-related health challenges of the coming decades, we may need to move beyond nutrient labels and ask a more fundamental question: what message does this meal convey?
Food—and how, when, where, why, and with whom we consume it—may be one of the most powerful messages shaping health and wellness or disability and disease.
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