Second meal effect: modified sham feeding does not provoke the release of stored triacylglycerol from a previous high-fat meal

The present study was carried out to determine whether cephalic stimulation , associated with eating a meal, was sufficient stimulus to provoke the rel ease of stored triacylglycerol (TAG) from a previous high-fat meal. Ten sub jects were studied on three separate occasions. Following a 12 h overnight fast, subjects were given a standard mixed test meal which contained 56 g f at. Blood samples were taken before the meal and for 5 h after the meal whe n the subjects were randomly allocated to receive either water (control) or were modified sham fed a low-fat (6 g fat) or moderate-fat (38 g fat) meal . Blood samples were collected for a further 3 h. Compared with the control , modified sham feeding a low- or moderate-fat meal did not provoke an earl y entry of TAG, analysed in either plasma or TAG-rich lipoprotein (TRL) fra ction (density < 1.006 kg/l). The TRL-retinyl ester data showed similar fin dings. A cephalic phase secretion of pancreatic polypeptide, without a sign ificant increase in cholecystokinin levels, was observed on modified sham f eeding. Although these data indicate that modified sham feeding was carried out successfully, analysis of the fat content of the expectorant showed th at our subjects may have accidentally ingested a small amount of fat (0.7 g for the low-fat meal and 2.4 g for the moderate-fat meal). Nevertheless, a n early TAG peak following modified sham feeding was not demonstrated in th e present study, suggesting that significant ingestion of food, and not jus t oro-sensory stimulation, is necessary to provoke the release of any TAG s tored from a previous meal.