Satiety and substrate mobilization after oral fat stimulation

The aim of the study was to provoke cephalic and metabolic responses by oral fat stimulation with different high-fat meals in the postprandial state. A randomized parallel design was executed with three groups of subjects (twenty-six women and ten men; twelve subjects per group). Oral fat stimulation was achieved by the modified sham feeding (MSF) technique. Five hours after a high-fat breakfast, the subjects were given one of three test meals in random order: a high-fat lunch, water or the same lunch as the MSF. The main fat sources in the high-fat lunch and MSF were olive oil, linoleic oil and oleic oil. For 3 h after the test meal, blood samples were taken for analysis of metabolite, and visual analogue scales of appetite profile were completed. A cephalic response appeared to be achieved by MSF in that we observed a relative increase in insulin and glucose; this response lasted up until 90 min, indicating possible vagal stimulation. NEFA increased significantly after MSF compared with water ingestion in the case of olive oil (P<0.0001) and linoleic oil (P<0.05), but not with oleic oil. MSF provoked a significantly higher increase in triacylglycerol and glycerol levels compared with water ingestion in the case of linoleic oil (P<0.05). Satiety was significantly increased in the eating condition and in the MSF condition (P<0.0002, all oils) compared with water ingestion. We conclude that cephalic and perhaps vagal stimulation by different fats increased the concentrations of the metabolites and stimulated satiety, with linoleic oil showing the strongest response.