Effect of ileal fat perfusion on satiety and hormone release in healthy volunteers.

Objective:The ileal brake is a feedback mechanism activated by nutrients, especially fat, with marked effects on satiety. The effects of low doses of ileal fat on satiety are largely unknown. We therefore studied the effect of ileal vs oral delivery of low doses of fat on satiety and gut peptide secretion.Design:Randomized, single-blind crossover design.Subjects:Sixteen healthy, normal-weight volunteers (6 male; mean age 26 years, mean body mass index 22.4).Intervention:Participants were intubated with a 290-cm-long nasoileal tube and consumed, on 3 consecutive days, either a liquid breakfast with 3 g fat followed by an ileal placebo infusion at t=105-150 min (treatment C) or a fat-free liquid breakfast followed by an ileal infusion of either an emulsion of 3 g (treatment I3g) or 9 g (treatment I9g) fat (safflower oil).Measurements:Satiety parameters by visual analog scales and plasma concentrations of CCK and PYY.Results:C significantly increased satiety and CCK secretion compared with the fat-free breakfast. Ileal fat perfusion of both 3 and 9 g (I3g and I9g) significantly increased satiety during and after fat perfusion, without differences in satiety between I3g and I9g. During ileal fat infusion, CCK increased dose dependently, whereas PYY concentrations increased significantly only after 9 g of fat. Secretion of CCK but not of PYY correlated to satiety levels.Conclusion:Postprandial satiety following a liquid breakfast can be effectively and significantly increased by small amounts (as little as 3 g) of fat perfused into the ileum. Ileal fat dose-dependently increased CCK but not PYY secretion. The satiating effect of ileal fat may be partly mediated by CCK.International Journal of Obesity advance online publication, 16 September 2008; doi:10.1038/ijo.2008.166

Effects of acute dietary restriction on gut motor, hormone and energy intake responses to duodenal fat in obese men

Background: Previous patterns of energy intake influence gastrointestinal function and appetite, probably reflecting changes in small-intestinal nutrient-mediated feedback. Obese individuals consume more fat and may be less sensitive to its gastrointestinal and appetite-suppressant effects than lean individuals. Objective: To evaluate the hypothesis that, in obese individuals, the effects of duodenal fat on gastrointestinal motor and hormone function, and appetite would be enhanced by a short period on a very-low-calorie diet (VLCD). Methods: Eight obese men (body mass index 34±0.6 kg m−2) were studied on two occasions, before (V1), and immediately after (V2), a 4-day VLCD. On both occasions, antropyloroduodenal motility, plasma cholecystokinin (CCK), peptide-YY (PYY) and ghrelin concentrations, and appetite perceptions were measured during a 120-min intraduodenal fat infusion (2.86 kcal min−1). Immediately afterwards, energy intake was quantified. Results: During V2, basal pyloric pressure and the number and amplitude of isolated pyloric pressure waves (PWs) were greater, whereas the number of antral and duodenal PWs was less, compared with V1 (all P<0.05). Moreover, during V2, baseline ghrelin concentration was higher; the stimulation of PYY and suppression of ghrelin by lipid were greater, with no difference in CCK concentration; and hunger and energy intake (kJ; V1: 4378±691, V2: 3634±700) were less (all P<0.05), compared with V1. Conclusions: In obese males, the effects of small-intestinal lipid on gastrointestinal motility and some hormone responses and appetite are enhanced after a 4-day VLCD.IM Brennan, RV Seimon, ND Luscombe-Marsh, B Otto, M Horowitz and C Feinle-Bisse