GIP release was lower ( P < 0.001 ) for IPO and lard compared with HOS and PO meals ; the maximal increments ( geometric mean and 95 % confidence interval ) for HOS , PO , IPO and lard were 515 ( 468 , 569 ) , 492 ( 448 , 540 ) , 398 ( 350 , 452 ) and 395 ( 364 , 429 ) ng/l , respectively .