Sumo wrestlers eat a calorie-dense stew called chankonabe to gain mass, not fat directly. Chankonabe contains ingredients like tofu, vegetables, and meat in a chicken broth. Sumo wrestlers consume large portions of chankonabe along with rice, beer, and side dishes to form their distinctive physiques, then take long naps. Fats serve important functions like energy storage and insulation, but sumo wrestlers focus on high-calorie whole foods rather than isolated fats to gain size for their sport.