Recently, research on food loss and waste and the related environmental impact has increased globally. Wasted food creates nitrogen emissions throughout the food supply chain, from agricultural production and food processing to consumption and waste disposal. Although the generation of food waste must be reduced, the lack of quantitative information on the production of household and catering food waste has led to an underestimation of waste volumes and inhibited the development of sufficient policy interventions designed to decrease food waste. The present study investigated the volume of catering food waste generated in Beijing and calculated its nitrogen footprint. In the present study, we focused on avoidable food waste, i.e., all wasted food and raw materials that could have been consumed had they been prepared differently. Other bio-wastes, such as vegetable peels, bean dregs, or bones, were not measured. During first-hand surveys of the catering sector of urban Beijing in 2013, 136 restaurants were studied. These establishments were divided into large, medium, small, canteen, and fast-food restaurant categories. A total of 2,704 samples were collected, each consisting of two parts:a consumer questionnaire and the weight of the sample of food waste generated by consumers of the establishment. Then, the nitrogen footprint and its discharge to the environment were calculated. The main conclusions of the present study are:(i) an estimated 74.39 g of food waste is produced per non-household meal in urban Beijing. Food waste generation differed significantly among restaurant types. For example, large restaurants generated the most waste-99.34 g, three times that produced by fast food restaurants (30.27 g). (ii) The food waste comprised many different food types, the most prominent (by weight) being vegetables (44.18%), followed by aquatic products (12.04%), pork (8.60%), beans and bean products (7.69%), poultry (7.50%),wheat flour (6.96%), rice (5.36%), beef (1.90%),mutton (1.89%), other meat (1.22%), eggs (1.20%), nuts (0.97%), other grains (0.24%), fruits (0.20%), and dairy products (less than 0.1%). (iii) The total N discharge to the environment was 16.37 per non-household meal, and the nitrogen footprint of the catering food waste produced per non-household meal in Beijing was 0.22 g N/g. By food category, the largest proportion of the calculated nitrogen emissions was generated by meat (30.65%), beans and bean products (26.61%), and grains (12.90%). By process, the food production stages producing the largest proportions of the emissions were agricultural production (almost 85%), waste management (7.60%), and fertilizer production (37.39%). Nitrogen discharge to the atmosphere, soil, and water was 7.34, 1.34, and 7.69 g per non-household meal, respectively. (iv) For the waste volumes, large restaurants generated the most N discharge-22.53 g three times that produced by fast food restaurants (5.67 g), followed by the medium (18.05 g) and small (13.05 g) restaurants.