During her first year at Tufts University, she renamed herself after the Greek mythological character Medea and joined the Students for a Democratic Society. She then dropped out of school and hitchhiked through Europe and Africa, teaching English classes to earn money. She later returned to the United States and received master's degrees in public health from Columbia University and in economics from The New School. Benjamin worked for ten years as an economist and nutritionist in Latin America and Africa for the United Nations Food and Agriculture Organization, the World Health Organization, the Swedish International Development Agency, and the Institute for Food and Development Policy.