The blogs, housed by the Microsoft division, were shut down at the request of Catalan Internet quality control agency Iqua, the spokesman added. He did not provide details on the content of the websites.
It was the first time in Spain that a company housing Internet sites has shut down web pages seen as promoting eating disorders following a complaint from authorities, Iqua said.
Computer firms that house such websites tend to close them only after a court order is issued, the agency added.
Blogs with tips on how to become extremely thin, primarily directed at young girls, have sprouted in cyberspace, alarming health officials who say they promote eating disorders.
In January, Spanish authorities banned an Internet site dubbed "the Porcelain Princesses", which planned to run a competition for young women suffering from anorexia.
The contest offered points to those reducing their calorie intake to a minimum, with starvation rations of 50-150 calories a day worth nine points, while a maximum 10 points was offered for not eating all day.