Slowly and rapidly digested fat emulsions are equally satiating but their triglycerides are differentially absorbed and metabolized in humans.

Little is known about the effect of dietary fat emulsion microstructure on plasma TG concentrations, satiety hormones, and food intake. The aim of this study was to structure dietary fat to slow digestion and flatten postprandial plasma TG concentrations but not increase food intake. Emulsions were stabilized by egg lecithin (control), sodium sterol lactylate, or sodium caseinate/monoglyceride (CasMag) with either liquid oil or a liquid oil/solid fat mixture. In a randomized, double-blind, crossover design, 4 emulsions containing 30 g of fat in a 350-mL preload were consumed by 10 men and 10 women (BMI = 25.1 ± 2.8 kg/m(2); age = 58.8 ± 4.8 y). Pre- and postprandial plasma TG, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and peptide YY (PYY) concentrations and food intake were measured. In a second experiment in a subset of the participants (n = 8, 4 men and 4 women), (13)C-labeled mixed TG was incorporated into 2 different emulsions and breath (13)C was measured over 6 h. In the first experiment, the postprandial rise in plasma TG concentrations following the CasMag-stabilized emulsion containing 30% solid fat was lower than all other emulsions at 90 and 120 min (P < 0.05). Plasma CCK (P < 0.0001), GLP-1 (P < 0.01), and PYY (P < 0.001) concentrations were also reduced following this emulsion compared with control. Food intake at a test meal, eaten 3 h after the preload, did not differ among the emulsions. In the second experiment, when measured by the (13)C breath test, 25% of the TG in the CasMag emulsion was absorbed and metabolized compared with control. In conclusion, fat can be structured to decrease its effect on plasma TG concentrations without increasing food intake.