A Villari effect sensor comprises a sensing rod constructed from a magnetostrictive material. An alternating current signal applied to an overlapping drive coil is inductively coupled by the sensing rod to the sensing coils and generates a signal thereon, responsive to the permeability of the magnetostrictive sensing rod which decreases responsive to the applied load. The sensing rod comprises one or more sections, each having a distinct cross sectional area, and a sensing coil is associated with each section. A signal processor calculates the magnitude of the applied force from either the maximum flux density, or by differencing the first and third harmonics of the signal from the sensing coil. The weight of an occupant on a vehicle seat (300) is measured by either incorporating a tensile force measuring Villari effect sensor in series with the seat springs, or incorporating a compressive force measuring Villari effect sensor in series with seat posts (314).