Mass reduction is a main issue in mechanical design. Over millions of years, Nature had to face this issue. Nature came up with an efficient solution using a stress-driven structure to reduce the mass of bones while saving their mechanical performances. This optimized structure is used in several species and persists throughout Evolution. Thus, it may be considered as optimal for this issue. In this article, a method bio-inspired from both bone medullar cavity and trabecular structure is proposed to reduce the mass of parts subjected to mechanical stresses. The objective of this method is to provide high mass reduction, just like bone does. First, the method removes iteratively unloaded areas of material from the mechanical part to mimic the medullar cavity structure. Second, a final mass reduction is done integrating small holes bio-inspired from trabecular structure in the remaining material. An experimental validation was carried out on a torsion disc and provided a 60% mass reduction. Using this mass reduction rate, the topology optimization method was used to define a standard geometry to evaluate the mechanical performances of the proposed method. Experimental results highlight that regarding torsional stiffness, the bio-inspired part is 27% stiffer than the standard one. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).