Moisture diffusion in lipids has been traditionally described by generic models that do not offer complete information about its structural dependency. Due to the lack of a predictive structure-based model in literature, we do not know the crystallization conditions needed to favorably alter structure and decrease moisture transport in lipids. The objective of this study was to develop a mathematical model to predict effective moisture diffusivity based on fractal structure and void fraction in lipids. Predicted water uptakes using the proposed model were in better agreement (RMSE 0.01-0.03) with experimental data when compared to models from literature (RMSE 0.01-0.16). Clearly, accounting for the fractality of fat crystal networks and vapor phase diffusion in the void fraction were critical to the success of the proposed model over all other models. Interestingly, moisture diffusion occurred predominantly in the void fraction compared to the liquid oil fraction of all the lipid samples. Published by Elsevier Ltd.