In her senior year of high school, Sarah Madaus often had panic attacks when her friends or family wanted to eat out because she could not control the sodium and sugar in restaurant dishes.

“My parents were so confused,” said Madaus, a 23-year-old editorial assistant in New York City who graduated from Temple University last year. “It was really stressful for me. I wouldn’t let myself have anything under the umbrella term of junk food, like pizza or sweets.”

Madaus was an athlete in high school when she was diagnosed with polycystic ovary syndrome (PCOS), a hormonal disorder that can cause irregular periods, infertility, acne, and weight gain. After she went on oral contraceptives to regulate the symptoms of PCOS, Madaus gained even more weight. That’s when she developed an obsession with exercising and eating “clean,” such as limiting herself to lunches of fruits, vegetables, and half a protein bar.

Although wanting to eat healthy isn’t generally a problem, Madaus’ extreme behavior was a sign of orthorexia nervosa, an eating disorder characterized by an intense obsession with “healthful” eating that can damage one’s well-being. In recent years, wellness culture on social media platforms, especially Instagram, have created a toxic environment for those most vulnerable to disordered eating: teenage girls.

“I was constantly worried about tracking calories. I’d become very stressed if I didn’t work out one day,” Madaus said. “I was extremely controlling, especially in my early college years, because I felt like things were out of my control. I thought that I could at least control this one thing, which was basically food and how much I was exercising.”

Unlike anorexia nervosa and bulimia, orthorexia, first named in the 1990s, is not formally recognized in the Diagnostic and Statistical Manual of Mental Disorders, a guidebook used by health-care professionals. Like anorexia, it can cause such physical symptoms as malnutrition, as well as such mental symptoms as depression, anxiety, guilt and shame. People who suffer from orthorexia also present symptoms typically seen in obsessive compulsive disorder (OCD), such as high levels of anxiety, perfectionism, ritualized patterns and recurrent, intrusive thoughts.

But orthorexia is not as easily diagnosed as similar disorders, said Samantha DeCaro, the assistant clinical director at the Renfrew Center in Philadelphia.

“Orthorexia can really get lost within diet culture because it looks like someone is pursuing health, but ironically their pursuit of health is making them very unhealthy,” DeCaro said. “It can be difficult to spot because we don’t always see the fear of weight gain that we typically see with other eating disorders.”

Research on orthorexia is limited, but studies have suggested that the disorder likely affects somewhere between 1% and 7% of the population.

Disordered eating has gained more visibility recently due to Taylor Swift sharing her eating habits in her documentary, Miss Americana. Swift said that while she was on tour, she obsessively counted calories and kept track of everything she ate, to the point that she would feel like she was going to pass out in the middle of a concert, behaviors that align with orthorexia.

“Each person struggles with orthorexia differently,” said Jennifer Kreatsoulas, a yoga therapist based in Wayne who specializes in eating disorder recovery. “Some people only eat organic foods, others avoid artificial preservatives, sugar, fats, salt or other ingredients they’ve deemed unhealthy. With orthorexia, one’s diet becomes more and more narrow because what is healthy keeps shifting for that person.”

Kreatsoulas said that wellness marketing on Instagram can feed the obsessive component of orthorexia.

“These external sources of information can become driving forces for how to think, how to eat, how to treat one’s body,” she said. “It can build the frenzy of confusion and really add to the set of rules that get developed. It creates the perfect storm for orthorexia to run away a bit.”

Indeed, a 2017 study by researchers at University College London found that higher Instagram use was associated with more orthorexia symptoms.

DeCaro said many wellness influencers use their platforms to share information about meal plans and “good and bad food,” often sponsored by companies. She said that kind of social media behavior can give followers the impression that if they eat in the prescribed way, they’ll look like the influencer.

“Those who are at a vulnerable age can really latch on to these concepts, and it can be really sort of difficult to break out of those beliefs,” DeCaro said.

Madaus said that when she was struggling with orthorexia, she often saved photos posted by fitness influencers on Instagram for inspiration.

“I was constantly looking at pictures of healthy food, with hashtags like #eatclean, #traindirty, or #countingcalories,” she said. “I was seeing these captions that were talking about how something is only 300 calories, super diet culture-y content, and I was ingesting it at a pretty young age. Being constantly bombarded with that really does a number on your brain.”

When Michelle Schwartz, a 28-year-old personal trainer in Connecticut, was recovering from a years-long battle with various eating disorders, including bulimia, binge eating and anorexia, she established strict rules for herself about what she could and could not eat. Schwartz, who grew up in Chester County, said that as a result of her rules, she began losing weight.

“I was like, ‘That’s kind of nice!’” Schwartz said. “I felt healthier and so much better as a person. I had more energy.”

But then she participated in an eight-week fitness challenge, during which she didn’t have any processed foods.

“I was saying no to too many things that weren’t technically bad for me,” Schwartz said. “I was writing out every single item that I was going to eat, and I don’t think that was healthy.”

Schwartz didn’t know that patients recovering from anorexia or bulimia are more at risk for developing orthorexia.

As a fitness trainer, Schwartz was familiar with using Instagram to share her eating and exercise habits. But during her recovery from disordered eating, she noticed how food posts by other people in the wellness community were misleading.

“Someone would post a picture of a meal that would have very minimal calories, and it would look good, but realistically someone has to eat more than that for one meal,” she said. “It made me nervous, because it was like, ‘Should I be eating that little?’ On the other side of the spectrum, someone would post an amazing healthy dish, but it would be a 900-calorie meal. And realistically there’s no way they eat 900 calories five times a day.”

Schwartz found balance in how she absorbed content on social media platforms by accepting that everybody’s body is different, and that it wasn’t healthy to compare how much she was eating to other influencers.

“I can’t take images or calories and be like, ‘This is exactly what I need to do,’ because I would become obsessive with that,” she said.

Madaus said that things became better for her after “the culture started changing and accepting larger bodies, different bodies.” Instead of reading about various diets in the news, Madaus began seeing more stories about mindfulness and intuitive eating, the practice of learning to eat when you’re hungry and stop when you’re full, rather than eating for emotional reasons. Seeing a therapist and taking up cycling also helped, she said.