Contributions of reduced hunger and premature satiety to cancerous hypophagia in rats.

Tumor-induced reduction in food intake in 2 rat-tumor organisms was distributed approximately equally between reduction in average size (premature satiety) and reduction in frequency (impaired perception of hunger) of effective meals. In both organisms, the frequency of futile meals (activity at food dish without any food ingestion) increased in the tumor-bearing state, and total meal frequency (effective plus futile meals) was unchanged from the tumor-free state. It is proposed that the presence of tumor reduces some meals to zero size and that satiety can occur in the cephalic phase of digestion before any food has been ingested. By this interpretation, cancer hypophagia would be entirely attributable to premature satiety.