Joe Yonan is The Washington Post’s food editor.

I got an upsetting email from a Washington Post reader recently. “As I enter the grocery store,” she wrote, “I am seized with a combination of dread and stupefaction. I am surrounded by food, but I have no idea what to buy. I feel the same way when I go to a restaurant. I look at the menu and see nothing I’m interested in eating. As a result, I eat far less than I should. I’m not anorexic or bulimic, but at 6 feet tall, I weigh about 120 pounds.”

She went on to describe some of the reasons behind her various eating anxieties and ended with a plea to me, the paper’s food editor: “I need help, like a reeducation or introduction to food.”

This reader, an accomplished retired professional, could easily have been a case study in Bee Wilson’s fascinating new book, “First Bite.” Wilson, a British food writer and historian, makes the argument that most of us have a fraught relationship with food: overstuffing ourselves or depriving ourselves, consuming too much of what’s bad for us and not enough of what’s healthful, while feeling guilty, anxious or both. What interests Wilson most, though, is the question of how we have gotten to this point and how we might change.

This is not a self-help book, though; Wilson resists preachiness and service-oriented advice-giving, relegating her bulleted suggestions to a brief epilogue (and she titles it “This Is Not Advice”). Instead, she dives into the science behind how we form our food preferences — sometimes sensible ones, most of the time not — to show that the biggest mistake of all has been in assuming that such preferences are inborn.

“Genes do make a difference — to the foods we like, the way we taste them, and even how much we enjoy eating — but they turn out to be much less significant than the environment in which we learn to eat those foods,” she writes.

She’s not afraid to poke holes in some of the most enduring myths, even those with a scientific basis. Early in the book, she writes about an influential 1920s and ’30s experiment in Cleveland that seemed to show that babies — when left to follow their own likes and dislikes in choosing from a variety of foods, offered nonjudgmentally — would choose wisely, resulting in a diet that improved their health. Even though child-rearing experts for decades pointed to the experiment as an argument for letting children control their own food selections, the doctor who conducted the study, Clara Davis, didn’t see it that way, and she admitted the “trick”: All the options she offered the babies were wholesome ones. “It was obvious to her that there was no ‘instinct’ pointing blindly to the ‘good’ and the ‘bad’ in food,” Wilson writes. “Had she offered the children a free choice of ‘sugar and white flour,’ those staples of a 1930s diet, it is unlikely they would have ended up in such fine fettle.”

The real lesson? “The experiment proved that when your only food choices are good ones, preferences become unimportant,” Wilson writes.

Outside a lab, with the influences of parents, siblings, friends, memory, marketers and food manufacturers at play (and so many of the choices anything but healthful), it’s a different story.

In her introduction, Wilson writes that she initially thought her book would focus exclusively on children’s food. And she devotes a good portion of “First Bite” to the ways in which babies, toddlers and older children learn to like what they like and hate what they hate. Genes may not play as much of a role as experience, but research shows that babies appear to remember amniotic fluid, and it influences their preferences — mothers who ate a lot of garlic while pregnant produced babies who were more likely to enjoy garlic in food, and so on.

One important takeaway for new parents might be the realization that between 4 and 7 months, babies “are extraordinarily receptive to flavor,” meaning that if they are exposed to varied bites of vegetable purees then, they’re more likely to be open-minded to new flavors as they get older. While breast-feeding, mothers who eat as varied a diet as possible may also help produce a less-fussy-about-food baby later on. And when it comes to formula, given the power of these early exposures, “the obvious implication is that formula-fed babies would benefit from having their milk flavored with vegetables.”

What about us adults, young and old? With decades of eating behind us, what is the hope for changing long-held habits? As she started researching, Wilson writes, “I started to see that many of the joys and pitfalls of children’s eating were still there for adults. As grown-ups, we may still reward ourselves with treats, just as our parents did, and continue to ‘clean our plates,’ though they are no longer there to watch us.”

Some of the problems are extreme. It’s obvious that “selective eating” (formerly known as picky eating) isn’t limited to children; Wilson writes about an adult teacher who wanted to become a missionary in Asia but worried that she couldn’t unless she expanded her diet of only “ketchup sandwiches, Oreo cookies, and instant noodles.” So she used a process of “taste exposure” — slowly and gradually trying tiny morsels of different foods — to build up her tolerance and variety.

Such eaters may be part of a spectrum that includes better-known disorders, such as bulimia and anorexia. Anorexia, Wilson writes, appears to be caused by a combination of genetics and environment: “when someone who is genetically predisposed to the illness suffers some kind of stress or trauma.” For girls, that trauma might be puberty. The most successful treatment seems to be what therapists call “family-based treatment,” a nonjudgmental process in which the family “refeeds” the anorexic.

Wilson draws parallels between bulimics and anorexics and the rest of us. “Most of the population . . . is similarly disconnected from internal signals about when, what, and how much to eat,” she writes. “The difficulty is that those whose disordered eating is less extreme are likely to have less help: when you sit down to eat, you are both the parent and the child, the doctor and the patient. . . . What all of us need is to find a way to eat regular meals, to take pleasure in a variety of foods, and to be able to eat them without being consumed by negative emotions.”

One of the biggest hurdles for those who need to curb a tendency to overeat is the difficulty in recognizing hunger, and the difference between short-term satiation and long-term satiety. But there is hope; adults who were taught mindfulness about hunger lost more weight in one trial than those who only dieted. The key, Wilson writes, might lie in “making friends with hunger. We are not the starving children. To feel mildly hungry two or three times a day — when you are lucky enough to know that another meal is coming soon — is a good thing.”

Wilson sprinkles just enough personal narrative through “First Bite” to establish her as a sympathetic figure without turning the book into a memoir. Among other things, she confesses to times “when my eating was out of control” and to painful conflicts with her third child, whom she regrets “force-feeding” during a period of fussiness. Her tone is refreshingly loose and friendly; she’s one of the few food scholars I can think of who can effectively quote both Margaret Mead and Homer Simpson.

Ultimately, her message is a hopeful, even liberating, one bolstered by examples large and small. The biggest is Japan, which “has somehow managed to achieve the ideal attitude toward eating: an obsession with culinary pleasure that is actually conducive to health.” But it wasn’t always thus. Before the 1900s, Japan’s reputation for cuisine was “far inferior to that of China,” she writes, with food that “was neither varied nor appealing . . . and there never was enough of it.” Wilson charts three crucial times when the nation adopted new tastes, the most recent during the postwar boom of the 1950s, when the Japanese — partly as a result of U.S. food aid — were exposed to Western and other foreign foods, and took to them with gusto.

The smaller examples include a severely autistic 3-year-old who went from having tantrums if his family tried to get him to eat more than toasted cheese sandwiches and hot dogs to being able to enjoy 53 different foods. Another bright spot: A Scandinavian program called Sapere teaches “sensory education” to children, resulting in a drop in childhood obesity rates in Finland. It’s even been used to help the elderly relearn the joys of healthful eating.

It’s a mistake to think we can’t change our eating habits, Wilson emphasizes. “In fact, we can do plenty. The first step is seeing that eating is a skill that each of us learns, and that we retain the capacity for learning it, no matter how old we are.”

I had just started reading “First Bite” when I got that wrenching email , the one from the reader with the subject line, “Please help me rediscover the beauty of food.” I waited to answer, partly because I had no idea where to start, and I’m glad I did. When I reread her email and started writing my reply, I felt so much more optimistic about her prospects than before. At least she, like Wilson, believes in the possibility of change.

How We Learn to Eat

By Bee Wilson

Basic. 319 pp. $27.99