Riders of the Apocalypse, book 1: Hunger
Jackie Morse Kessler2010

Lisabeth Lewis has a black steed, a set of scales, and a new job: she's been appointed Famine. How will an anorexic seventeen-year-old girl from the suburbs fare as one of the Four Horsemen of the Apocalypse?

Traveling the world on her steed gives Lisa freedom from her troubles at home--her constant battle with hunger, and her struggle to hide it from the people who care about her. But being Famine forces her to go places where hunger is a painful part of everyday life, and to face the horrifying effects of her phenomenal power. Can Lisa find a way to harness that power--and the courage to fight her own inner demons?