The big challenge of the next decades is meeting the global nutritional demand, while reducing the pressure on food resources and the GHG emissions. In this regard, the overall goal consists of redesigning the food systems and promoting sustainable dietary patterns is a crucial aspect. This article focuses on reviewing the state-of-the-art of the combined Life Cycle Assessment (LCA) and the Water-Energy-Food (WEF) Nexus approach in assessing the effects of diet transitions. Diet LCAs differ in methodology, design, and assessed environmental impacts. The WEF nexus, which aims at finding synergies and trade-offs between the water, energy, and food resources systems, has been applied to different contexts and levels. However, a limited number of nexus methods have been developed at the food and diet levels, and no commonly recognizable methodology for the nexus assessment has been achieved. An integrated LCA and WEF Nexus approach can be a decisive tool to improve the understanding of the interconnections in the nexus, as it enables the consideration of entire supply chains. This study is part of the Ceres-Procon Project: Food production and consumption strategies for climate change mitigation (CTM2016-76176-C2-2-R) (AEI/FEDER, UE), financed by the Spanish Ministry of Economy and Competitiveness, which aims to determine strategies to improve the sustainability of current food production and consumption.