Effects of oleic acid and olive oil on gastric emptying, gut hormone secretion and appetite in lean and overweight or obese males

In lean subjects, free fatty acid (FFA) promotes gut hormone release, delays gastric emptying, and reduces appetite and energy intake more than an isocaloric load of triglyceride (TG). In obesity, the gastrointestinal sensitivity to lipids may be reduced. Therefore, we compared the effects of the FFA oleic acid and the TG olive oil on gut hormone secretion, gastric emptying, appetite, and energy intake in lean and overweight/obese subjects. In a double-blind, randomized cross-over study, 8 lean and 13 overweight/obese healthy subjects were examined at two occasions to evaluate the effect of intragastric isocaloric loads of radiolabelled oleic acid or olive oil on gastric emptying, plasma CCK, PYY, and GLP-1 concentrations, appetite, and energy intake. In comparison to olive oil, oleic acid caused a slower gastric emptying (p < 0.001), a higher plasma concentration of CCK (p < 0.05) and PYY (p < 0.05), and a lower subsequent energy intake (p < 0.05) whereas no difference was observed in GLP-1 concentrations. No significant differences were observed between lean and overweight/obese subjects. An intragastric load of FFA is followed by slower gastric emptying, increased CCK and PYY secretion, and a lesser subsequent energy intake than an isocaloric load of TG in both lean and overweight/obese healthy subjects.