The study of starvation-resistant biological programs has elucidated numerous mechanisms influencing aging. Here we present the discovery and characterization of starvation-induced adult reproductive diapause (ARD) in Caenorhabditis elegans. ARD differs from the C. elegans dauer diapause in that it enables sexually mature adults to delay reproductive onset 15-fold and extend total adult life span at least threefold. The effectiveness of ARD requires apoptotic death of the entire germ line, except for a small population of protected germline stem cells (GSCs). When feeding is resumed, surviving GSCs regenerate a new germ line capable of offspring production near the level of nonstarved animals. The starvation-sensing nuclear receptor NHR-49 is required for ARD entry and recovery. Our findings establish mechanisms for preserving stem cell potency and reproductive potential during prolonged starvation.