Increasing resource use efficiency is one of the important ways to enhance agricultural productions and reduce environmental hazards. For this purpose, improvement of N use efficiency is an effective approach. Nitrogen losses not only occur in field but also in the processing course. The objective of this study was to calculate nitrogen losses and efficiency during production to consumption for wheat (Triticum aestivum L.) and maize (Zea mays L.). Information on the amount of applied nitrogen, cultivation area, yield, returned residues, share and distribution of food production was collected through communication for filling questioner and literature review. Results showed that total nitrogen harvested and N efficiency by wheat and maize were 387, 81.7 Kt and 25%, 60%, respectively. The highest losses of nitrogen was observed in field for wheat but this losses for maize was lower than wheat due to higher efficiency in nitrogen absorption. N harvested rate showed different efficiency that was associated to entering which way for plant or animal production. Nitrogen use efficiency in food production cycle for wheat and maize were 14.2% and 7.6%, respectively. Higher efficiency of N was observed in plant food production path compared with animal food. Nitrogen use efficiency in plant food production system was about 13 times higher than animal production system. It seems for decreasing N losses in food production systems, the nitrogen efficiency in the field and processing courses should be increased.