To accurately map the large deformation properties of soft tissues, accurate, in-vivo measurements of internal strain are essential. In this study, the Right Cauchy Green strain of adipose tissue was calculated from displacements generated through the non-rigid registration of mDIXON images under increasing compression. The method was validated by synthetically deforming an uncompressed image with compression. Five real-world datasets were acquired of adipose tissue under increasing compression, which resulted in significant increases in the maximum principal strain (one-way ANOVA, p<0.001). The described method provides an accurate quantification of physiological strains in adipose tissue that is essential for mapping strain-varying viscoelasticity.