Effect of postgastric energy loads on intake of sham meals of different palatability in rats

Food intake depends on the palatability of the diet and on the energy delivered to the body. It is not known, however, whether the palatability of a diet is able to modulate the inhibitory effect of energy input on food intake. To address this question, we have measured intake during sham feeding for diets of different palatabilities in rats receiving varying levels of duodenal energy load. Rats were offered sucrose solutions (6, 10, or 30%) or mixed liquid diets without or with physiological duodenal energy loads using a mixed liquid diet. Compared with that seen during real feeding, meal size during sham feeding was increased for palatable diets but not for less palatable diets. Intraduodenal infusion of the mixed liquid diet inhibited the intake of all diets given by sham feeding. This inhibition was dependent on the level of duodenal energy load and was significantly greater for more palatable diets than for less palatable ones. We conclude that the inhibitory effects of intestinal nutrient load on intake are significant for all diets but have a more pronounced effect on the intake of highly palatable diets.