Marked differences in gustatory and gastrointestinal sensitivity to oleic acid between lean and obese men.

ABSTRACT

BACKGROUND: Both orosensory stimulation and feedback from the gastrointestinal tract contribute to energy intake regulation. OBJECTIVE: We evaluated the hypothesis that overweight or obese subjects would be less sensitive to both oral and intraduodenal oleic acid exposure than would lean subjects. DESIGN: Eleven overweight or obese and 8 lean men were studied on 2 occasions, during which antropyloroduodenal pressures, plasma cholecystokinin and peptide YY, and appetite were measured during 90-min intraduodenal infusions of saline or oleic acid (181 load 0.78 kcal/min); energy intake (buffet lunch) was determined immediately afterward. Oral detection thresholds for 181 and recent dietary intake (2-d recall) were also quantified. RESULTS: In lean subjects, the number of isolated pyloric pressure waves (IPPWs) was greater during 181 infusion than during saline infusion (P < 0.05); no significant differences were observed between the 181 and saline infusions in the overweight or obese subjects. In both groups, 181 stimulated plasma cholecystokinin and peptide YY and suppressed energy intake compared with saline (P < 0.05), with trends for reduced cholecystokinin and energy intake responses in the overweight or obese subjects. Detection thresholds for 181 were greater in overweight or obese (7.9 ± 0.1 mmol/L) than in lean (4.1 ± 0.4 mmol/L) subjects (P < 0.05). Overweight or obese subjects had greater recent energy (P < 0.05) and fat (P = 0.07) intakes than did lean subjects. There was a direct relation (r = 0.669) of body mass index with 181 detection thresholds and inverse relations (r < -0.51) of IPPWs with body mass index and 181 detection thresholds (P < 0.05). CONCLUSIONS: The ability to detect oleic acid both orally and within the gastrointestinal tract is compromised in obese men, and oral and gastrointestinal responses to oleic acid are related. This trial was registered at www.actr.org.au (Australian New Zealand Clinical Trials Registry) as 12609000557235.