Sex and cognitive dietary restraint influence cholecystokinin release and satiety in response to preloads varying in fatty acid composition and content

The aim of the study was to evaluate the effect of preloads differing in fatty acid composition, content, and delivery form on acute behavioral, subjective, and biological outcomes of satiety. Four energy- and volume-matched preloads were tested in normal weight men and women (n = 12 and 13, respectively), using a random, crossover design. Preloads were semisolid shakes differing in fat source [walnut or safflower (SAFF)], delivery [ground walnuts (WNT) or walnut oil (WOL)] or content [39% fat energy (SAFF, WNT, WOL) or 4% low-fat control (LFC)]. Blood was collected and subjective satiety assessed at 0 (fasting), 15, 30, and 45 min after preload consumption. Lunch (test meal) was provided thereafter. Energy intake at lunch was not affected by preload; however, subjects selected more carbohydrate, fiber-rich foods at the test meal lunch after walnut preloads than after LFC or SAFF preloads. Compared with the LFC preload, appetite satisfaction was significantly greater after SAFF and WNT, but not after WOL. Women were hungrier after SAFF than after WOL, whereas men were less hungry after SAFF and LFC than after WOL or WNT. Plasma cholecystokinin (CCK) concentrations reflected preload fat content and availability, particularly among men; CCK was higher after WOL and SAFF preloads than after LFC or WNT preloads. Plasma insulin was higher after LFC and SAFF preloads, corresponding to hunger suppression in men. Dietary restraint was associated with a blunted CCK response to preloads, whereas insulin was not affected by restraint. The results indicate that test meal energy intake after preloads containing similar to 40% walnut or safflower fat or 4% fat did not differ; however, walnut consumption may promote food patterns consistent with consuming diets higher in fiber.