Ana Carolina Reston, who had worked in China, Turkey, Mexico and Japan for several modeling agencies, died Tuesday, according to Sao Paulo's Servidor Publico Hospital.
The hospital said the infection that killed the 5-foot-8-inch model was caused by anorexia nervosa, a disorder characterized by an abnormal fear of becoming obese, an aversion to food and severe weight loss.
"Take care for your children because their loss is irreparable," Reston's mother, Miriam, told the O Globo newspaper. "Nothing can make the pain go away. No money in the world is worth the life of your child."
Reston began her modeling career at the age of 13 after winning a local beauty contest in her hometown of Jundiai, on the outskirts of Sao Paulo.
"I noticed something was wrong when she returned from Japan," Miriam told the Estado de Sao Paulo newspaper. "She was too thin when she returned and when I told her to eat something, she would say: 'Mom please don't fight with me; there is nothing wrong with me, I'm fine.' "
The model's cousin, Dani Grimaldi, told the Estado de Sao Paulo newspaper that Reston also battled bulimia, an eating disorder marked by binge eating that is followed by vomiting or the use of laxatives.
The world of high fashion and modeling has long been targeted by critics who say it encourages women and girls to emulate rail-thin models.
In September, a Spanish fashion show responded to such criticism by banning models with a body mass index of less than 18. Body mass index is a calculation doctors normally apply to study obesity, and anyone with an index below 18.5 is considered underweight.
Reston would have had a body mass index of 13.4 at the time of her death, according to a calculator on the Web site of the U.S. Centers for Disease Control and Prevention.