Organisms adjust their rate of growth depending on the availability of nutrients. Thus,when environmental conditions limit nutrients, growth is slowed and is only restoredafter food again becomes abundant. Many aspects of the molecular mechanisms thatgovern this complex control system remain unknown. However, it has been shown thatthe insulin/IGF-1 (insulin-like growth factor 1) receptor pathway, together with theFOXO family of transcription factors, play an important role in this process. Recentstudies with the fruit fly Drosophila melanogaster have provided new insights into theregulatory circuitry that controls both growth and gene expression in response to nutrientavailability.