High-fat diet preference and overeating mediated by postingestive factors in rats.
The role of postingestive factors in the preference for and overconsumption of high-fat (HF) foods, relative to high-carbohydrate (HC) foods, was investigated using a self-regulated intragastric feeding procedure. On one-bottle training days, rats drank one flavored saccharin solution [conditioned stimulus (CS) + HF] paired with intragastric infusions of an HF liquid diet, a second flavored solution (CS+HC) paired with an HC liquid diet, and a third flavored solution (CS-) paired with intragastric water. The diets had the same energy and protein content; the CS solutions and infusions along with chow were available ad libitum. The rats drank more CS and self-infused more diet on HF than HC training days. In two-bottle choice tests, the rats preferred the CS+HF to the CS+HC and both CS+HF and CS+HC to the CS-. The rats consumed more CS+HF than CS+HC by taking more bouts per day; bout sizes did not reliably differ. In a subsequent experiment, rats preferred the CS+HF even though diet intakes in training were matched. In a final experiment, the CS+HC and CS+HF intakes were equated in training by diluting the HC diet. Now the rats did not reliably prefer the CS+HF to the CS+HC, yet caloric intakes were much higher on CS+HF than CS+HC training days. Thus, relative to an isocaloric HC diet, the postingestive effects of HF diets stimulate overeating and condition a stronger flavor preference. Reduced satiety rather than increased reinforcement may be the direct promoter of overeating. However, postingestive reinforcement may enhance the selection of HF foods when a choice of HF and HC foods is available.
Lucas
F
F
Department of Psychology, Brooklyn College and the Graduate School, The City University of New York, Brooklyn, New York 11210, USA.
Ackroff
K
K
Sclafani
A
A
D000818:Animals; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage*; D004068:Digestive System Physiological Phenomena; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D051381:Rats; D017207:Rats, Sprague-Dawley
D004041:Dietary Fats