Back in 1826, French lawyer and politico Jean Anthelme Brillat-Savarin released a straight fire treatise entitled “Physiology of Taste, or Meditations on Transcendental Gastronomy.” The most memorable line has been dropped by and re-dropped and remixed ever since: “Tell me what you eat and I will tell you what you are.” You might know that phrase in its loose English translation, “you are what you eat,” which is less pointed, but not wrong. The reason for the misquote? A 1940 nutrition manual by Victor Lindlahr, who wanted Americans to eat more vegetables and to equate quality produce with a higher quality of life.

Brillat-Savarin and Lindlahr were different sorts of thinkers because they lived in different societies. Their work is about nutrition, sure, but their perspectives are products of different attitudes towards class and class mobility. But the basic thesis that they share, that input and output are correlated, holds up — albeit in sometimes surprising ways.

“Your food is understood as a bag of chemicals; you are a bag of chemicals, organized into physiological systems; eat the right chemicals and you will enjoy good health; eat the wrong ones, and you will suffer disease and shortened life,” wrote Harvard sociologist Steve Shapin, somewhat less pithily, in the journal Historical Research in 2014.

Servicemen eating at Thanksgiving dinner at the end of World War I.

The purpose of food science and its interdisciplinary cousin “food studies” is to learn why we eat certain things and what are the implications of that food choice on health. Food sciences focuses (unsurprisingly) on science, while food studies (an emerging field) looks at the relationship between food, culture, and society. Looking expressly at the science of food choice, you’ll see that the argument made by Hipprocates and Galen that food could affect mood, and therefore personality, was not far off. In Ancient Greek society people ate dates and elderberries to put themselves in a better mood, lettuce and chicory to chill out, and apples, pomegranates, beef, and eggs to get sexy.

This went back to the idea that the body was made up of four “humors”: blood (hot and moist), yellow bile (hot and dry), phlegm (cold and moist), and black bile (cold and dry). The key to health — both physical and emotional — was balancing all these humors. Have a fever? Eat a cold and moist cucumber. Feeling bummed? Have some spice.

Today we have a better understanding of the chemical reaction that, catalyzed by food, causes our moods to change. Serotonin rich food like clams, oysters, bananas, and nuts help elevate mood and enhance impulse control. Chocolate makes you feel good because it contains biologically active constituents that act like psychoactive drugs. Caffeine consumption kickstarts an enzyme cascade that prompts you to feel alert but can also increase anxiety.

Researchers are also increasingly aware that taste preference can be connected to personality traits. In a 2015 study published in Appetite, researchers from the University of Innsbruck studied 953 Americans. The study participants self-reported their taste preferences in two different surveys and then answered a personality questionnaire assessing the “Big Five” personality domains, aggression, narcissism, psychopathy, Machiavellianism, and “everyday sadism.” They found that people who enjoyed bitter foods were more likely to be sadists.

“Although they [eating and drinking] satisfy the most fundamental needs, they also relate to a number of more complex psychological phenomena such as morality and emotional distress,” wrote the researchers. “The results suggest that how much people like bitter-tasting foods and drinks is stably tied to how dark their personality is.”

This coffee-drinking woman is probably  a sadist.

This sadistic link makes sense on an evolutionary level: Bitterness is often a mark that food is toxic. Comparatively, sweet foods usually have a higher caloric density — something key for survival if you’re a hunter-gatherer. Liking bitter food also probably means you’re tougher: a 2012 study found that bitter-sensitive rats were more subordinate and easily stressed. The researchers believe this likely holds true for humans too.

A different 2015 study, also published in Appetite, studied the connection between food choice and personality by surveying 951 subjects. They found that openness to experience, conscientiousness, and neuroticism all directly affected food choice. They found that conscientious people stayed away from sweet foods and ate more fruit and less meat. Extroverted people wanted to eat all that is savory and sweet, while neurotic people did the same — but for different reasons.

“Results suggest that neurotic and emotionally unstable seem to adopt counter-regulatory external or emotional eating and eat high-energy dense sweet and savory foods,” writes the study authors. Comparatively “the higher sociability of extraverted people, which is basically a health beneficial psychological resource, seems to have health-averse effects.”

Neurotic people are emotional-eaters.

Food study academics argue that, besides physically altering our personality through chemical reactions, that long-standing stereotypes between certain food and cultures biases how we see certain people. In this case you are what you eat becomes this is how you’re seen because of what you eat.

“Use of food has long been recognized as a way that a person assigns identity to herself/himself and others,” writes Cornell professor Carole Bisogni in Who We Are and How We Eat. “In Western societies, the body has become a maker for personal and social identity, with a healthy and fit body equated with self-control, self-denial, and willpower.”

This was true when European colonists were afraid that eating local foodstuffs would transform their bodies and minds to match those of the people they were attempting to subjugate and true now when people think that if they shop at farmer’s markets they’ll simultaneously be seen as hip and ethical.

In a 2001 paper, Igor Garin, director of research at the French National Centre for Scientific Research, argues that food is far more than just fuel for the body — it is expressly manipulated to create social boundaries between classes and cultures. Religious food restrictions create a sense of kinship; a cultural recognition of a one food in particular — like the United States and hotdogs — creates a sense of unity in material ways. Garin notes the long relationships between northern Europeans considering the spicy and smelly foods of southern Europe and the Middle East to be barbaric and gross. Part of this goes back to science: Ingested food affects body odor. When people smell different, xenophobia rises.

Choosing what to eat may seem like an arbitrary decision, but it’s very much affected by your physiology and culture. You are what you eat — but it’s on you to makes sure that what you eat doesn’t make you an asshole.

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