Feeding response to change in absorbable food fraction during growth of Walker 256 carcinosarcoma.

Normal animals ingest larger amounts of food diluted with nonnutritive bulk than they do undiluted food, to the extent that nutrient intake remains almost constant. This compensation is complete up to dilutions of 50% and is evident, although incomplete, at 75% dilution. The normal hyperingestive response to 50% diet dilution is depressed within the 1st week of growth of Walker 256 carcinosarcoma, when the tumor weighs about 200 mg. In the 3rd week of tumor growth, when the tumor weighs about 40 g, there is no hyperingestive response to any level of food dilution. At 75% dilution, food intake is depressed to 25% of the intake of the undiluted diet. Dilution of food with unabsorbable bulk is an experimental homolog of uncomplicated malabsorption. These results show that malabsorption associated with tumor growth may contribute to cancer cachexia by virtue of the blocking by the tumor of the normal physiological hyperingestive response to reduction of the absorbed fraction of ingesta.