Subjects and Methods: CCK and neurotensin release were quantified in: 1) 12 subjects receiving an ID fat infusion with or without 60 mg orlistat, an irreversible inhibitor of gastrointestinal lipases, in comparison to vehicle. 2) 12 subjects receiving ID long chain fatty acids (LCF), ID medium chain fatty acids (MCF) or ID vehicle. 3) 10 subjects receiving ID LCF with and without the CCK-1 receptor antagonist dexloxiglumide (DEXLOX) or ID vehicle plus IV saline (placebo). Hormone concentrations were measured by specific RIA systems.