Food waste reduction strategy involves a quantification of food waste generation. This work aimed to evaluate the volume and the type of post consumption food waste and to identify its main causes in a university canteen (INAT, Tunis, Tunisia). Based on a direct method, wasted food was weighed with an electronic scale, during 23 working days. Three main food groups were quantified: prepared food (PF), plate waste (PW), which is the amount of food rejected by students and left on their plates, and non-served food (NS), which is the amount of food not distributed to diners and remaining in the serving bowls. Daily direct quantification has revealed that average meals served was 209 kg/day, whereas as average food daily waste was 15.90 % of PF, 0.074 kg per student and 13.4% of PF were non-served. The average index of waste/consumption was approximately 17 %, and classified as bad, and the per capita plate was 29.3 g. The daily quantities of food waste varied from 0 to 15 kg. The most rejected foodstuffs were stews (25.3%), pasta and cereal products (20.7%), and especially bread with a waste percentage of 43%. Cause and effect diagram coupled with interviews and survey allowed identifying principal causes for the food waste generation: perceived sensory quality, poor food presentation, poor menu planning and poor management of the fluctuation of the students' number (the quantities served were not adjusted) as well as customers' behaviours and habits. The cost of this food waste was estimated to 15.2% of the canteen annual budget. Potential interventions for food waste preventions are discussed.