Effects of oral fat perception by modified sham feeding on energy expenditure, hormones and appetite profile in the postprandial state.

Previously, we have shown that satiety and metabolites increased after high-fat modified sham feeding (MSF). We assessed possible metabolic effects due to oral stimulation with a high-fat sham-fed 'meal', in comparison with a high-fat fed meal and with water, in the postprandial state. Fourteen healthy women (aged 18-40 years; BMI 22.5 (sd 3) kg/m2) were fed in energy balance during 4 d with a 50 % enegy as carbohydrate, 15 % energy as protein and 35 % energy as fat menu. On day 4, subjects were given one out of three test lunches, 5 h after a high-fat breakfast, in random order: a high-fat MSF lunch, water (W) or the same lunch to be eaten (E), during their 36 h stay in the respiration chamber, where substrate oxidation, 24 h energy expenditure (EE) and appetite profile were measured. Oral fat stimulation by MSF increased EE (W 6.3 (sd 0.8) v. MSF 6.9 (sd 1.0) kJ/min and E 6.8 (sd 0.7) kJ/min; P < 0.04) for 1 h, increased plasma insulin concentrations (t = 15; W 10.0 (sd 3.4) v. MSF 13.2 (sd 4.0) v. E 22.3 (sd 3.3) units/l; P < 0.0001), attenuated changes in plasma NEFA concentrations (t = 15, W 432 (sd 108) v. MSF 418 (sd 146) v. E 282 (sd 72) mumol/l; P < 0.0001), plasma TAG concentrations (t = 60; W 1092 (sd 548) v. MSF 1116 (sd 493) mumol/l and E 1350 (sd 352) mumol/l; P < 0.02) and plasma glycerol concentrations (t = 15, W 87 (sd 29) v. MSF 74 (sd 34) mumol/l and E 67 (sd 18) mumol/l; P < 0.03). Over a longer period of time, MSF had no effects on substrate oxidation, diet-induced thermogenesis or total EE. In addition to the previously observed metabolic effects of oral stimulation with fat, EE is stimulated up to 1 h after the MSF meal.