To determine whether digestive effects instead might be responsible for aversions, rather than taste, the researchers offered the rats water flavored with saccharine, which they typically prefer to unflavored water. They then placed a feeding tube directly into the stomachs of the animals and infused some with corn oil and others with saline solution. Other animals received an injection that causes unpleasant sensations. Previous studies have shown that animals can be conditioned to avoid foods they associate with illnessfor example, by avoiding saccharine-flavored water after becoming ill from lithium chloride. Consequently, the researchers reasoned that if corn oil caused unpleasant digestive effects, the rats fed this liquid might also avoid the saccharine-flavored water. Additionally, the researchers tested the levels of GLP-1 and PYY, hormones previously linked with food avoidance, in both the Roux-en-Y and sham-operated animals.
Questionnaires from human patients revealed that those who had gastric bypass were significantly more likely to report a reduction in dietary fat intake compared to those who had gastroplasty instead.
The researchers found that rats who underwent Roux-en-Y surgery consumed significantly lower proportions of high-fat chow and higher proportions of low-fat chow compared to the sham-operated animals. Additionally, those animals who underwent the bypass surgery showed a lower preference for high concentrations of the fat emulsions compared to those who received the sham operation. The Roux-en-Y animals had about th
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American Physiological Society