Determinants of high-fat diet hyperphagia: experimental dissection
of orosensory and postingestive effects.
Weingarten, Zoe S. Warwick Harvey P.
Department of Psychology, McMaster University, Hamilton, Ontario,
Canada L8S 4K1
APStracts 2:0037R, 1995.
High-fat diets often promote greater caloric intake and/or weight gain
than high-carbohydrate diets in both laboratory animals and humans.
Since altering the fat content of a diet simultaneously changes both
its sensory properties and postingestive effects, it is unclear
whether high-fat hyperphagia is due to the diet's palatability, its
postingestive effects, or both. The present studies isolated the
independent capacity of the orosensory and postingestive effects of a
liquid high-fat diet (high-FAT) to produce overeating relative to an
isocaloric liquid high-carbohydrate (high-CHO) diet. Rats fed high
-FAT orally ate more calories and gained more weight over 16 days than
rats fed high-CHO orally. One-bottle sham-feeding intake of high-FAT
and high-CHO did not differ, but in two-bottle sham-feeding tests
high-FAT was clearly preferred. When orosensory influences on intake
were equated via chronic self-regulated intragastric feeding, high
-FAT still promoted greater intake than high-CHO, although absolute
intake across both diets was lower during intragastric feeding
relative to oral feeding. An analysis of short-term intake revealed
that rats accustomed to infusion of high-CHO increased meal size
immediately when switched to high-FAT. The present results, coupled
with previous findings, suggest that the postingestive effects of fat
enhance daily calorie intake in two ways: 1) during a meal, fat
produces less suppression of intake per calorie than carbohydrate,
and 2) after a meal, fat produces less suppression of intake per
calorie during the intermeal interval than carbohydrate.
Received 29 July 1994; accepted in final form 1 February 1995.
APS Manuscript Number R412-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 February 1995.