The postprandial period is a dynamic state of hormone and lipoprotein metabolism that can be influenced by dietary composition. The objective of this study was to determine whether the source of dietary fat [dairy (D) vs. nondairy (ND)] would modify the lipemic, insulin and cholecystokinin (CCK) response to high or low fat meals. Men and women (n = 24) consumed 4 test meals with a similar polyunsaturated:saturated (P:S; 0.12:1) fat ratio. The diets were high (38% energy) or low (20% energy) in fat, with or without fat from dairy sources. CCK responses were greater after consumption of meals containing D than ND, and for high compared with low fat meals. Women had higher CCK responses than men and were more sensitive to the differences in dietary treatments. Consumption of low fat meals resulted in greater insulin responses than high fat meals. However, after consumption of the low fat meals, the insulin response of D was about half of the ND response; no differences in insulin response were detected after the high fat meals. Triacylglyceride response was influenced primarily by the fat content of the diet. Consumption of dairy products containing fat was associated with an enhanced CCK response, which may have implications for the regulation of food intake. Blunting glucose and insulin response in low fat meals containing fat from dairy products may be useful for glycemic control.