According to psychiatrist Angela Guarda, director of the Johns Hopkins Eating Disorder Program, while picky eating is commonly associated with children, a handful don’t outgrow it once they hit adolescence. French fries, PB&J sandwiches and other “kid” foods often make up their primary staples, while fruits and vegetables are almost always seen as inedible. As much as they might want to expand their diets, just the smell of a new food can trigger a gag reflex in extreme cases. Guarda thinks the restriction to comfort foods might be found in our evolutionary history, and for some reason those affected with SED don’t outgrow the preferences given at birth. “It’s possible that we have evolved to prefer high- calorie foods and to avoid bitter foods or sour foods in infancy because it’s protective to do so,” she says, explaining that high-calorie foods are used as a survival method, to prepare for times of famine. Bitter foods, like vegetables, are a taste that’s acquired later on to prevent babies from eating potentially poisonous things…

And there are more people than anyone predicted. In 2010, psychologist Nancy Zucker and her team at the Duke Center for Eating Disorders launched the first large-scale study of adult selective eaters through an online survey. Zucker says she expected to get a couple hundred responses, but 18,000 people have since participated. She hopes the industry can use the center’s future findings to create a way of categorizing people with food restrictions that impair health and functionality, but don’t necessarily entail the goal of weight loss. “It may be that we have a broad selective eating umbrella and then we can describe people based on genetic or taste variations to try to get different tailored interventions,” Zucker says. “I wouldn’t say you could go so far as to snap them into food adventurer, but I would say that you can make a picky eater into someone who’s food-curious.”