On the ultra-processed fortnight, participants ate about 508 calories a day more, and they gained roughly 0.9 kilograms. That is the core result of the inpatient trial led by Kevin Hall, published in Cell Metabolism in 2019. What the trial actually held constantThe design is what makes this study worth sitting with. Why willpower is the wrong frame for this resultThe paper offers a mundane candidate: people got through the ultra-processed meals faster. A four-week ward study and an eight-week home-feeding trial, both small and both contested at the margins, point in the same direction without settling the mechanism.