Five students at Columbia University are staging a hunger strike to protest what they say is a Eurocentric core curriculum and a growing climate of racism on campus. They are also protesting the university’s Harlem expansion plan, calling it disruptive.

Two sophomores at Barnard College and three Columbia students last ate Tuesday evening and said they would not break their fast until the school committed to a core curriculum that includes a seminar addressing issues of “racialization and colonialism,” among their other demands.

“I’m already hungry,” a senior at Columbia, Bryan Mercer, 22, said yesterday, less than 24 hours into the strike. Mr. Mercer, who is majoring in anthropology and comparative ethnic studies, said he has been scaling back his diet for weeks in preparation for the strike. His said his last meal was a sparse helping of fruit and bread. Mr. Mercer said his fast is also a protest of a delayed response from the administration to a string of racist incidents targeting black and Jewish professors on campus. The strikers said they would stop attending classes when they felt too weak to concentrate. Most healthy adults can survive about 60 days without food as long as they have plenty of water, but fasting becomes dangerous after five days, according to nutritionists. A coalition of students supporting the strike is planning vigils every evening, as well as a rally on the steps of Low Library today at noon.

In recent years, Columbia has amended its core curriculum to include a Major Cultures component, which requires students to take courses about Asian, African, and Latin American civilizations. The required reading list now includes texts such as “The Souls of Black Folk,” by W.E.B. Du Bois, and “The Wretched of the Earth,” by Frantz Fanon, about Algeria’s struggle for independence from colonial rule, and the Haitian Revolutionary Constitution.

Of the students on the hunger strike, one is black, one is Latino, one is Asian, and two are white. The other strikers are: a Barnard sophomore from California, Samantha Barron, 19; a Barnard sophomore from Colorado, Aretha Choi, 19; a Columbia senior from Illinois, Emilie Rosenblatt, 22, and a Columbia junior from California, Victoria Ruiz, 20.

Ms. Ruiz said she had not informed her parents that she was participating in the strike, and was hoping to keep them in the dark.

The students attended a weigh-in yesterday morning, and are hydrating with an electrolyte mixture. “When you go into starvation mode, your ability to burn calories effectively and to keep your weight at a maintenance level diminishes,” a registered dietician, Marissa Lippert, said.

The last known hunger strike at Columbia was in 1996, when students demanded an ethnic studies program at the school. After 15 days, the administration agreed to increase the number of professors in its Asian American and Hispanic studies programs, and later established an ethnic studies center.

“Columbia encourages students to express their points of view and supports their right of public protest,” a spokeswoman for Columbia, LaVerna Fountain, said in a statement. Administrators are planning to meet with striking students this week, and the health center will be monitoring students’ vital signs.