All living organisms require nutrients to grow and reproduce. When nutrient quantity or quality is low, organisms reduce their growth rate and enter a dormant state characterized by arrested physiological activity and critical for cell survival. We now report that preserving proteins during dormancy speeds the return to a growth state. We establish that the bacterium Salmonella enterica reduces proteolysis by adenosine triphosphate (ATP)-dependent proteases by decreasing ATP amounts when starved for magnesium, carbon or nitrogen. The yeast Saccharomyces cerevisiae also reduces ATP amounts and ATP-dependent proteolysis when starved for nutrients. Drugs that increase ATP amounts delay entry into the growth state by promoting ATP-dependent proteolysis. Thus, the better the ability to preserve proteins during dormancy, the faster prokaryotes and eukaryotes exit the dormant state as soon as nutrients become available. Starvation-promoted protein longevity likely also plays a role in the germination of bacterial spores and in antibiotic persistence.