Differential gender response produced by meal and ad lib feedings of a high-fat diet in Osborne-Mendel rats.
We investigated if there were gender differences in metabolic consequences produced by meal feeding of a high-fat (HF) diet in male and female Osborne-Mendel rats. An HF diet was fed either ad lib (AL) or in 1 meal (MF) during the last 3 h of the dark cycle for 4 weeks (lights off from 2400 h to 1200 h). All rats were sacrificed at 1 of 3 time-points: prior to MF rats receiving their food at 0900 h, after food was taken from MF groups at 1200 h or 1500 h. Food intake, body weight, body fat weight, retroperitoneal adipose tissue lipoprotein lipase activity, plasma cholesterol, or HDL-cholesterol levels did not differ between MF- and AL-fed groups, but were higher in male than in female rats. There were no differences between the male and female groups in plasma levels of insulin and glucose or systolic blood pressures. Plasma triglyceride levels at 1200 h were significantly different between MF and AL Groups within either gender, but this was not observed at 0900 h or 1500 h. Body weights were correlated with internal fat weights and plasma cholesterol levels in both males (r = 0.57, p < 0.05) and females (r = 0.59, p < 0.05). Hence, it is the amount of HF diet ingested, rather than the pattern of meal feeding, that was the most significant factor related to gender differences in weight gain, increases in fat mass, and metabolic differences.