The chapter attempts to demonstrate some aspects related to the role of food losses and waste (FLW) in food insecurity, in two parts: (i) identifying direct linkages between FLW and food insecurity - that is a predictor of malnutrition (i.e. underweight, overweight and obesity, micronutrient deficiencies); and (ii) how can FLW reduction support food security and nutrition. The literature review covers selected works during the last 10 years. It addresses quantitative and qualitative FLW impacts on the four dimensions of food security and, overall, on sustainable food systems and healthy diets. Among the chapter`s highlights: (i) food insecurity data gaps could be exposed by FLW analysis and quantification; (ii) data on food insecurity should be connected to the data on FLW. The conclusions emphasise the need for future coordinated research, policy development, and private sector as well as civil society engagement to accomplish SDG 12.3, the UN Decade of Action on Nutrition and the Paris Agreement outcomes.