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 (18:1 load: 0.78 kcal/min); energy intake (buffet lunch) was determined immediately afterward. Oral detection thresholds for 18:1 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 18:1 infusion than during saline infusion (P < 0.05); no significant differences were observed between the 18:1 and saline infusions in the overweight or obese subjects. In both groups, 18:1 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 18:1 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 18:1 detection thresholds and inverse relations (r < −0.51) of IPPWs with body mass index and 18:1 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.