Fat-Rich Food Palatability and Appetite Regulation

Two views are being debated around fat-rich food and appetite regulation. One is that fat intake has a weak satiety-signaling property, with the consequence being a passive overconsumption of fat-rich food, in turn leading to obesity (Westerterp, 2006). The other view is that fat intake is tightly regulated through specific signals, which when overstimulated leads to aversion (Jebb et al., 2006). Fat intake depends not only on the quantity but more importantly on the quality of fat ingested, whether it is saturated, monounsaturated, or polyunsaturated fat (Casas-Agustench et al., 2008). Another important feature relates to whether the fat is eaten with sucrose or with something that has a sweet taste (Erlanson-Albertsson, 2005a). In general this will lead to a blunted response. Endocannabinoids released after palatable food ingestion, such as food containing fat and sucrose, will promote hunger and energy storage. The following hormones have been found to regulate the appetite for fat. Galanin (Gaysinskaya et al., 2007), agouti-related peptide (AgRP) (Tracy et al., 2007), and ghrelin (Shimbara et al., 2004) stimulate fat intake, while enterostatin (Berger et al., 2004), apolipoprotein A-IV (Apo A-IV) (Tso and Liu, 2004a), peptide YY (PYY) (Boey et al., 2008), cholecystokinin (CCK) (Beglinger and Degen, 2004), and neuropeptide Y (NPY) (Primeaux et al., 2005) inhibit fat intake. Both galanin (Schneider et al., 2007) and ghrelin (Jerlhag et al., 2007) also stimulate the intake of ethanol, via pathways involving a link to the reward system. The inhibition of fat intake occurs through reduced gastric emptying and serotonin release (Ritter, 2004). A proper satiety for fat is possible only with complete fat digestion, fatty acids being important to release satiety hormones (Feinle-Bisset et al., 2005). For proper control of fat intake, fat digestion needs to be retarded without being inhibited (Albertsson et al., 2007). Why we overeat fat? Energy dense. Gastrointestinal processing too rapid. Satiety signals too weak. Hunger signals too strong.