In a context of increasing concern regarding food loss and waste (FLW) generation, different attempts have been made to standardize quantification methodologies. On the one hand, an important number of small-scale studies have been published that constitute direct measurement methodologies. On the other hand, the FAO Food Balance Sheets, which aggregate some of the prior studies, provides an indirect metric that has been applied using FLW coefficients in numerous food-related studies. However, to date, no standard methodology has been agreed upon to quantify FLW. This study performs an assessment of 237 studies in the field, aiming to identify existing FLW quantification methodologies, and if there is a need of developing alternative paths. Firstly, a descriptive review was performed. Secondly, an assessment of critical point of views was presented. For this, different critical voices in the scientific literature were retrieved, some of which highlight the high level of uncertainty and a certain degree of opacity in some of the most widespread FLW quantification and assessment reports. In this line, essential elements of quantification are being omitted. Moreover, the focus is being excessively placed on the role of the consumer, compared to the role played by agribusiness and large distribution chains.