The following substance acts as a 'satiety signal' for lipids

Enterostatin, a peptide that selectively reduces fat intake. It is formed in the intestine by the cleavage of secreted pancreatic procolipase, the remaining colipase serving as an obligatory cofactor for pancreatic lipase during fat digestion. After feeding, enterostatin appears in the lymph and circulation. Enterostatin will selectively inhibit fat intake during normal feeding and in experimental paradigms that involve dietary choice. Both peripheral and central sites of action have been proposed. The peripheral mechanism involves an afferent vagal signaling pathway to hypothalamic centers. The central responses are mediated through a pathway that includes both serotonergic and opioidergic components. Chronically, enterostatin reduces fat intake, body weight, and body fat. This response may involve multiple metabolic effects of enterostatin, which include a reduction of insulin secretion, an increase in sympathetic drive to brown adipose tissue, and the stimulation of adrenal coicosteroid secretionReference: Enterostatin-a peptide regulating fat intake; Erlanson-Albesson C, York D; Obes Res.1997 Jul;5(4):360-72