Why You Eat What You Eat: The Science Behind Our Relationship with Food

274 Pages·2017·1.71 MB·English

by  Rachel Herz

WHY
YOU EAT
WHAT
YOU EAT
THE SCIENCE BEHIND
OUR RELATIONSHIP WITH FOOD
RACHEL HERZ, PHD
W. W. NORTON & COMPANY
Independent Publishers Since 1923
New York | London
FOR JAMIE
AND EVERYONE WHO LOVES TO EAT.
CONTENTS
Introduction
1 THE FAB FOUR
2 TASTY
3 FOLLOW YOUR NOSE
4 FOOD FIGHT
5 EYE CANDY
6 THE SOUND AND THE FEELING
7 MIND OVER MUNCHIES
8 ARE YOU FULL YET?
9 COMFORT FOOD
10 BUYING INDULGENCES
11 FOOD IS LOVE
Acknowledgments
Notes
Index
WHY
YOU EAT
WHAT
YOU EAT
INTRODUCTION
In September 2013, The Telegraph, a British newspaper, reported on a “revolt”
fulminating over the newly introduced rounded shape of Cadbury’s iconic Dairy
Milk chocolate bar, which had previously more closely resembled a Hershey’s
bar. Hundreds of disgruntled customers complained that the rounder pieces were
“sickly” and “too sugary” compared to the original square pieces—according to
1
one critic, the new bar was “all wrong.” But the food titan Kraft, which had
bought Cadbury in 2010, insisted that the recipe had not changed. If Kraft hadn’t
changed the recipe, why were so many people protesting? Enter the budding
field of neurogastronomy—the scientific endeavor to understand the interactions
between our brain, food, and eating.
Ever since I can remember I have been sensorially infatuated with food—
feeling up the bread, taking bites out of chocolates and putting them back in the
box, sniffing cloves of garlic and unground coffee beans, bewitched by the sizzle
of fajitas. As a sensory and cognitive neuroscientist who has been studying the
psychology of smell since 1990, I am captivated by how our minds change our
perception of the world around us—especially what we put into our mouths.
Why You Eat What You Eat stems from this intersection and my quest to answer
the questions: how and why do our senses, mind, and environment impact our
experience of food and our motivation to eat? And how does food alter our
physiology, mood, and behavior?
In this book, you will meet various people whose experiences with eating
inform the complex and multilayered relationships with food that we all have,
including an extremely picky eater, a man who lost his sense of smell, someone
who never feels full unless he eats rice, and an accomplished political scientist
who is forced to sabotage her diet in order to work as hard as she does. We will
learn how scents change the way foods taste, how music and color alter our
perception of wine, how visual illusions can determine both how much food we
put on our plates and how fast we consume it, and why so many people order
tomato juice on airplanes.
In Why You Eat What You Eat I will explain how taste and our emotions are
intertwined: why eating sweets can make us kinder, how depression can make
grapes taste more sour, and how bitterness can change our moral outlook. I’ll
also discuss how what we eat can change our behavior, like the surprising way
making ethical food purchases, such as buying organic, can alter the way we
deal with other people, as well as how our behavior can change what we eat,
such as why bringing a reusable bag to the grocery store leads to more chips and
cookies ending up in the cart.
We will uncover the processes that cause us to be seduced by resplendent
treats, and discover how the number of people who are at the Super Bowl party
changes the number of chicken wings we’ll eat, and that whether our team wins
or loses alters our eating behavior the next day. I’ll tell you the secret to resisting
going back for thirds, and maybe even seconds, at the all-you-can-eat buffet.
You will also learn various useful techniques for managing cravings and
improving your experience of food, such as why paying attention to what you eat
makes it taste more delicious, how aromas can diminish food urges, the ideal
type of plate to use if you are trying to curb your intake, and why the first bite of
blueberry pie is always better than the last. I’ll explain how marketing
companies are using this science to take advantage of the link between our
senses and our desires, and how publicizing the reality of how much we have to
exercise to offset the calories in the food we eat can lead to wiser food and
beverage purchases.
We will explore how the time of day, our age, our hormone levels, the mood
we are in, physical activity, our personality, our beliefs, and what drugs and
alcohol we have consumed can influence our perception of food, what and how
much we crave and eat, and even whether or not we’ll gain weight from doing
so. We will question some of the latest headlines on diet and human health,
including “Is salt bad for you?” as well as whether what we eat can change our
susceptibility to disease. This book addresses how each of us—from omnivorous
hedonists to strict vegans—brings different talents and weaknesses to the table,
and how culture and our twenty-first-century obesogenic environment present
challenges that humans have never before faced.
Why You Eat What You Eat will take you on a voyage of sensory, scientific,
and self discovery that will immerse you in how psychology, neurology, and
physiology shape and influence our personal relationships with food, as well as
how food alters the relationships we have with ourselves, society, and one
another. Equipped with this knowledge, you will have a better understanding of
how and why our senses, mind, and environment are woven into our experience
of eating. With a fuller comprehension of your own gastronomic motivations,
you will enjoy a happier, healthier, and more satisfying relationship with food.
So let’s start at the beginning.
So let’s start at the beginning.
1
THE FAB FOUR
T
he very first life forms on this planet had what we might call a sense of taste
—the ability to recognize chemicals in their environment so as to know whether
a little tidbit would be nutritious, and to stay away from other tidbits that might
want to devour it. Taste and smell—the chemical senses—were the first senses
to evolve. And taste is everywhere. Moths have taste receptors on their wings.
Flies have taste receptors on their knees. Tarantulas taste with their feet.
Octopuses taste with their whole body—even their eyelids. We humans have
taste receptors all over us as well.
We have taste receptors in our pancreas, liver, and—if you’re a man—
testicles. We have taste receptors in our lungs that, when we inhale something
noxious, send a signal to the brain to make us cough, so as to expel what
shouldn’t be in there. We have taste receptors in our nose that help fight
infections, and taste receptors in our gut that influence our perception of food.
The taste receptors in our gut also tell the brain whether we should keep eating
an ice cream sundae or a cheeseburger, and when to stop, and it is believed that
disturbances in the signaling pathways of these taste receptors play a role in the
development of a variety of diet-induced illnesses, from irritable bowel
1
syndrome to diabetes. But only the taste receptors located inside the 5,000 to
10,000 taste buds on the tongue and, what may come as a surprise, taste buds
that are located on the roof of the mouth and in the throat are hooked up to the
taste cortex in the brain to give us the perception of what we call taste. We can’t
tell how sour an apple is with our liver.
There are many mysteries and misconceptions about taste. For one, not all
animals experience the same taste sensations as we do. Cats, from Fluffy the
house cat to Cecil the lion, can’t taste sweet. Whales and dolphins only taste salt.
Moreover, the notion that we perceive salty, sour, sweet, and bitter on different
Moreover, the notion that we perceive salty, sour, sweet, and bitter on different
parts of the tongue is wrong. Here is the story of how the false “tongue map”
was born.
In 1942, Edwin Boring, a psychology professor at Harvard University, read a
confusing description of taste sensitivities that had been published by a German
graduate student in 1901, and somewhere between the student’s fuzzy account
and Boring’s translation the facts were lost. Boring incorrectly inferred that
specific areas of the tongue were responsible for detecting specific tastes—the
back of the tongue for bitter, the tip for sweet, the sides of the tongue for sour
and salty—and lo, the notorious tongue map emerged. Then, in 1974, Virginia
Collins, a researcher at the University of Pittsburgh, reexamined the original
German data and found that though there are tiny differences in taste sensitivity
throughout the tongue, these differences are inconsequential and all tastes can be
detected anywhere on the tongue—except, as it turns out, along the center line,
which is “taste blind.” If you dip your finger in salt water and place it on the
center line you won’t taste anything, but move your finger to the right or left and
you will. For the past forty years the truth about taste and the tongue has been
plainly known, but the fiction of the tongue map still routinely makes its
appearance in textbooks and online taste anatomy descriptions.
Although the tongue map is wrong, the taste cortex in the brain does appear
to be laid out in a maplike fashion, with different clusters of neurons specialized
to respond to the different basic tastes in discrete regions: one region for sour,
one for bitter, one for sweet, and one for salty. In fact, the most recent research
suggests that we may not need a tongue at all in order to perceive tastes.
Charles Zuker, a neuroscientist at Columbia University whose laboratory has
transformed our understanding of taste, found that electrically tickling the bitter
neurons in the brains of mice caused their mouths to purse and their bodies to
shudder as though they were tasting bitter, but when they were given a real bitter
liquid and the “sweet” brain region was stimulated, they behaved as though they
2
enjoyed the bitter taste. Your mouth detects the chemicals for salt, sour, sweet,
and bitter, but it’s your brain that tells you the difference between anchovies and
applesauce, and signals that sugar is pleasurable and bitter is nasty. The
tantalizing implication is that our problems with resisting sweet foods and
beverages could be solved by switching on specific neurons when we want to
turn chocolate cake into the devil’s food. This is not mere science fiction.
Pharmaceutical companies are working feverishly to develop drugs that will take
the joy out of jelly and make kale taste like candy, in an effort to motivate
healthier eating habits.