Molecular simulation complements experimental studies of food systems by facilitating a molecular level understanding of structure formation. We have used both all-atom (AA) and coarse-grained (CG) molecular dynamics (MD) to follow the structural evolution of a crystallizing triacylglycerol (TAG) melt (using CG-MD) and the molecular details of phytosterol self-association in sterol-based oleogels (using AA-MD). For TAGs, CG-MD demonstrates substantial supercooling during crystal formation. When the crystal is subsequently heated, we can reproduce realistic melting temperatures for model tristearin and mixed tristearin+trilaurin systems. Additionally, information about the mechanism of the early stages of crystal formation can be deduced, and in particular the order of glycerol and acyl chain partitioning during cooling from the melt. In the oleogel systems, we model the formation of nanometre-sized tubules in a sterol ester (oryzanol, ORY) - sterol (β-sitosterol, SIT) mixture in an oil phase. We have identified the critical interactions between ORY and SIT that control tubule stability, the origin of water instability and the interactions that control hierarchical structuring into tubule bundles that form the network gel. This has informed our experimental studies that involve de-novo synthesis of novel gelators with the aim to control better the rheological (texture) properties and stability of oleogels in food products. The work demonstrates the applicability of molecular simulation to oil and fat related structural studies and should help to promote use of this approach by others in the future.