PRELIMINARY STUDIES ON THE GASTROINTESTINAL RESPONSES TO FATTY MEALS IN OBESE PEOPLE

Studies were carried out on eight obese (BMI 30-34.6 kg/m2) and seven age and sex-matched normal weight volunteers (BMI 20-25 kg/m2) to inve stigate the gastric emptying, mouth to caecum transit time (MCTT), pla sma cholecystokinin (CCK) and sensory responses to high (30 g margarin e; 1327 kJ (317 kcal)) and low (301 kJ (72 kcal)) fat soups. Gastric e mptying was measured by gamma scintigraphy, MCTT was measured by the b reath hydrogen technique, plasma CCK was measured using a bioassay tec hnique and subjective sensations were recorded on visual analogue scal es. The high fat meal emptied more slowly than the low fat meal in bot h the normal subjects (t1/2 = 86.3 +/- 9.2 vs. 36.7 +/- 2.8 min) and t he obese (t1/2 = 81.1 +/- 11.2 vs. 50.4 +/-12.2 min) but there were no differences in the emptying of either meal between the two groups of subjects. Increasing the fat content of the meal did not affect the mo uth to caecum transit time (MCTT) in either group, nor were there diff erences between the groups in MCTT (180 +/- 23 vs. 188 +/- 35 min, nor mal vs. obese MCTT after low fat soup; 228 +/- 17 vs. 227 +/- 29 min, normal vs. obese MCTT after high fat soup). Despite similar rates of g astric emptying, the obese group showed a higher CCK production follow ing the high fat meal than the normal weight group (540.4 +/- 65.9 vs. 336.9 +/- 51.4 pmol.min, 2 h integrated CCK production, obese vs. nor mal; P < 0.05). The obese group also reported feeling less hungry thro ughout the study than the controls. It is possible that the high CCK l evels in the obese group could reflect decreased receptor sensitivity to CCK which could increase CCK production by decreasing negative feed back.