Consumption of a High-Fat Diet Containing Lard during the Growth Period in Rats Predisposes Them to Favorably Respond to the Diet in Later Life

To investigate whether preferential fat intake by adult rats could be linked to fat-feeding of rats during the growth period, this paper describes the next two studies. Three groups of 4-wk-old male rats in study 1 received one of three diets: control diet (CTD). low-fat high-carbohydrate diet (LFD), and high-fat low-carbohydrate diet (HFD). After 6 wk (dietary treatment period), 6 rats in each of the groups were sacrificed and the remaining rats were placed on a self-selection regimen of fat-protein diet (FPD) and carbohydrate-protein diet (CPD) for 3 wk (self-selection period). After the dietary treatment period, liver weight and plasma insulin concentration of the LFD group and perirenal fat tissue weight and plasma triacylglycerol and leptin concentrations of the HFD group were higher than those of the CTD group. Although no significant difference in fat energy ratio (F ratio) of combination diets self-selected by the three groups was observed, the F ratios of the combination diets were higher than that of the CTD. After the self-selection period, liver weight and plasma insulin concentration of the LFD group and plasma triacylglycerol concentrations of the HFD group decreased. These data suggested that the dietary selection pattern of the rats was associated with a reduced basal plasma insulin concentration. Three groups of rats in study 2 were placed on a self-selection regimen of the LFD and the HFD after being fed one of three diets (LFD, CTD and HFD) for 6 wk. Although the F ratio of the combination diet consumed by the CTD and the LFD groups was similar to that of the combination diet consumed by rats in study 1, the F ratio of the combination diet consumed by the HFD group was higher than that of other groups. These findings suggest that consumption of the fatty food during the growth period predisposed them to favorably respond to the diet that had become familiar to them in later life.