Wednesday, Jan. 18, 2023 at 9 p.m. on KPBS TV + Sunday, Jan. 22 at 9 p.m. on KPBS 2 / On demand now with the PBS Video app. Scientists are coming to understand fat as a system akin to an organ - one whose size may have more to do with biological processes than personal choices. Explore the mysteries of fat and its role in hormone production, hunger and even pregnancy.