Tasting fat: cephalic phase hormonal responses and food intake in restrained and unrestrained eaters.

Restrained eaters exhibit strict cognitive control over their food intake, primarily by limiting intake of high-fat foods. Earlier studies indicate a relationship between dietary restraint and cephalic phase insulin release, which is hypothesized to influence hunger and food intake. To compare cephalic phase hormonal responses to high- and low-fat stimuli and determine if the sensory experience of tasting fat alters hormonal responses and influences subsequent food intake in restrained and unrestrained eaters, normal weight women classified as unrestrained (n=11) or restrained (n=11) eaters were tested under 3 conditions: (1) fasting, (2) sham-feeding a non-fat cake, and (3) sham-feeding a high-fat cake. Following an overnight fast, arterialized venous blood was drawn prior to and for 30 min immediately following a 3-min sham feed. Plasma samples were analyzed for insulin, glucose, glucagon and pancreatic polypeptide (PP). Subjects were subsequently given a selection of high-fat and low-fat foods and allowed to select what they wished to eat. Cephalic phase PP was significantly greater following oral sensory stimulation by the high-fat food (205.4+/-83.6) compared to the fasting control (11.1+/-38.8, p=0.04). No significant differences in hormonal responses to the food stimuli were found between restrained and unrestrained eaters but the restrained eaters consumed more food after the high-fat condition (p<0.05) relative to the fasted condition and compared to the unrestrained group (p<0.05). In conclusion, the sensory experience of tasting fat increases food intake in restrained eaters and increases vagal efferent activity compared to a non-fat food in both populations.