A large variety of food is needed to provide the crew choices and to avoid menu fatigue. The monotony effects from repeated food exposures are factors of duration of exposure, the initial pleasantness of the foods consumed repeatedly over time, and frequency and recency of eating the food ... food is consistently identified in [post-spaceflight] debriefs as one of, if not the most, important factor to crew morale. The variety and quality are important to motivate consistent caloric intake and prevent nutritional deficiency and weight loss.