Yoshinori Ohsumi has received this year’s Nobel Prize in Physiology or Medicine for figuring out how and why cells eat themselves. In key experiments from the 1990s, the Japanese biologist brought attention to this important process — called "autophagy," or "self-eating" — which occurs in many diseases, from type 2 diabetes to cancer.

Think of autophagy like the cell’s own recycling program: useless parts are destroyed to create energy to build new parts. First, cells enclose damaged parts of themselves in a membrane. These membrane-sealed sacs are then sent to a part of the cell called the lysosome, which is responsible for "digesting" old cell parts and other microorganisms.

We’ve known about autophagy for decades, but didn’t realize how important the process is until Ohsumi’s yeast cell studies in the 1990s. He identified the genes that regulate the process and helped us better understand how proteins build the membrane that encloses the cell parts sent off for "recycling." In later work, Ohsumi showed that human cells go through a similar process. "This recycling process did not receive as much attention as it deserved, but I discovered that we should be paying more attention to this autophagy process," he told Japanese public broadcaster NHK.

Autophagy is crucial to further medical research because it is involved in everything from aging to Parkinson’s to immune disease. Too much of this recycling can lead to more growth of cancerous cells; too little can lead to issues connected with aging.

Ohsumi received a doctorate in molecular biology from the University of Tokyo. He is professor emeritus at Tokyo Institute of Technology's Frontier Research Center. "When I started researching, I never thought this was research that would lead to a Nobel Prize," he said. "To be honest, that was never something that was motivating me."