Levi was born in Turin, Piedmont, to wealthy Jewish physician Ercole Levi and Annetta Treves, the sister of Claudio Treves, an important socialist leader in Italy.
Levi never completely abandoned his medical studies and served as assistant to Prof. Micheli at the University of Turin's Clinic from 1924 to 1928, working on research involving hepatopathy and diseases of bile tract.