Purple sea urchins (Strongylocentrotus purpuratus) are herbivores who inhibit rocky reefs from British Columbia to Baja California. When top down pressure decreases, often by means of a decrease in predator abundance, purple sea urchins increase grazing intensity and are capable of consuming all of the macroalgae within a kelp forest. This has resulted in the formation of urchin barrens throughout the large portions of their range. In barrens, urchins experience starvation, causing physiological changes such as a decrease in gonad mass and, over time, a complete resorption of their gonad tissue. We examined how S. purpuratus responds metabolically when deprived of food for long periods of time. This was done by comparing respiration rates of urchins who had access to food and urchins who have been starved for seven and 14 weeks. We observed a significant decrease in oxygen consumption after the urchins were starved, indicating decreased metabolic activity. After 14 weeks of starvation, the urchins were again fed for seven more weeks, which resulted in a revival of their metabolic activity that matched pre-starvation levels. In addition, we sampled urchins from Stillwater Cove, CA from areas of high macroalgal density as well as barren areas but found there to be no difference in urchin metabolic rates between the two areas. Our results suggest that when facing starvation, urchin metabolic rates significantly decrease. However, if they periodically receive food, they can sustain moderate levels of metabolic activity.