As a social experiment, Kerri Leonard and Christopher Greenslate, two vegan English teachers from Encinitas, Calif., challenged themselves to eat for $1 a day for a month. They alternated writing about the experience in a blog, which led to the publication of their book, On a Dollar a Day. Released last week, the book explores issues of hunger and poverty and the toll they take on health and nutrition. The idea grew from a trip to the grocery store, when the two compared their spending habits with the poverty experienced around the world. After realizing billions of people live on a dollar a day, the pair decided to live similarly for a month and chronicle their experience.