He frequently used dexamethasone, a cortisol-like drug, to treat specific blood disorders that benefited from suppressing the immune system. “He said the first thing you see when you give dexamethasone,” recalls Mary Dallman, “is that the kids would start eating like crazy—and you knew the treatment was going to work.” This led her to study the effect of cortisol and related compounds on calorie intake in rodents.

