Since childhood, Katie Barrett has felt bloated.
"It wasn't just my stomach that was bloated, [it was] my whole entire body," the 32-year-old said. "I was like the Pillsbury dough boy. I mean I was puffed up."
Barrett's bloating turned out to be a symptom of celiac disease, in which the body can't digest gluten, a protein found in wheat, barley and rye. For people like Barrett, one bite of pizza or a teaspoon of flour can ignite a response from the immune system, causing damage to the small intestine and ultimately other organs.
"You develop diarrhea, weight loss," said Dr. Alessio Fasano of the University of Maryland School of Medicine. "You feel bloated; you are gassy. You can have also abdominal pain and vomiting."
Barrett's symptoms started when she was 9, and they were so vague that even doctors couldn't diagnose her.
"I started having a ton of stomach pains to the point where I just wouldn't eat anymore," Barrett said. "My mom thought I was anorexic. I wasn't. It just hurt so much to eat I couldn't stand it."
After "every test you could possibly think of," a simple blood test Barrett took in 1996 -- 14 years after her symptoms began -- revealed that she had celiac disease.
The only treatment available is a gluten-free diet.
"I felt better within 10 days," Barrett said. "My diarrhea started to disappear; the bloating started to disappear. My stomach wasn't hurting as much. I felt great."
Gluten can be hard to avoid. It's found in lipstick, gum, toothpaste, and is in most processed food.
"You can't just grab a sandwich or a sub or a piece of pizza," Barrett said.
Barrett's celiac disease is under control, and she's currently enrolled in medical school with the hopes to treat others with the disease.
"I don't want people to go through what I went through -- the months and months of 'What is this?', the years of feeling sick," Barrett said. "Every story of every celiac is the same as mine, and that's just unacceptable to me. So, it's my mission to make sure that that changes."