Oral Presentation Australian & New Zealand Obesity Society 2014 Annual Scientific Meeting

Pyloric motility and energy intake responses to intraduodenal fat in lean, overweight and obese humans (#117)

Nada Cvijanovic 1 2 3 , Nicole J. Isaacs 1 3 , Christopher K. Rayner 1 4 5 , Christine Feinle-Bisset 1 4 , Richard L. Young 1 2 3 4 5 , Tanya J. Little 1 4 6
  1. Discipline of Medicine, University of Adelaide, Adelaide, SA, Australia
  2. Nerve-Gut Research Laboratory, University of Adelaide, Adelaide, SA, Australia
  3. South Australian Health and Medical Research Institute, Adelaide, SA, Australia
  4. Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, SA, Australia
  5. Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, SA, Australia
  6. Boden Institute of Obesity, Nutrition, Exercise and Eating Disorders, University of Sydney, Sydney, NSW, Australia

Background: Human obesity is strongly linked to high-fat diet (HFD) consumption. Evidence from animal studies shows an attenuation of the appetite suppressive effects of fat following a HFD, and in modelled obesity. Gastrointestinal (GI) responses to fat in obese humans are inconsistently reported, potentially due to differences in habitual fat and energy intake (EI) of study participants. Here, we compared the effects of intraduodenal (ID) fat infusion on pyloric motility (an important determinant of EI) and subsequent ad libitum EI in lean, overweight and obese humans, and examined relationships with habitual dietary fat and EI.  

Methods: The effects of ID fat infusion (2 kcal/min for 120 min) on isolated pyloric pressure waves (IPPWs) were assessed in fasted lean (L: BMI: 21.5 ± 0.5 kg.m2, n = 18), overweight (OW: BMI: 26.8 ± 0.4 kg.m2, n = 13) and obese (OB: BMI: 34.2 ± 1.5 kg.m2, n=9) healthy volunteers. Ad libitum EI (buffet lunch) was quantified immediately thereafter. Habitual dietary fat and EIs were assessed using 3 x 24-hour recall diaries. Data are presented as mean ± SEM.

Results: Habitual EI (kJ) (L: 8740 ± 784; OW: 8372 ± 538; OB: 8387 ± 1241) and the percentage of energy consumed as fat (L: 34 ± 2; OW: 32 ± 2; OB: 35 ± 2) did not significantly differ between study groups. ID fat increased IPPWs (L: 81.7 ± 38.4 mmHg; OW: 79.8 ± 23.2 mmHg; OB: 151.1 ± 40.4), with no statistical difference between groups. There was also no difference in EI (kJ) (L: 4342 ± 415; OW: 4534 ± 458; OB: 4382 ± 514) or fat consumption at the buffet meal.

Conclusion:  In the absence of significant differences in habitual dietary intake, GI motor and EI responses to ID fat do not differ in humans across a wide BMI range.