According to parallel axis theorem, M.I. of an axis (A’B’), parallel to an axis AB passing through centre of mass is given by IA’B’ = M.I.+ MR2 where M is mass of body and R is the perpendicular distance between AB and A’B’ )
∴ IA’B’ > IAB
∴ to minimize I, R = 0
Hence M.I. of a body is minimum about an axis passing through the centre of mass.