Effects of alternations (10 days) of high-fat with normal diet on liver lipid infiltration, fat gain, and plasma metabolic profile in rats

The purpose of the present study was to test the hypothesis that short-term alternations of high-fat with normal chow feeding result in higher fat accumulation in liver than continuous intake of the same high-fat diet. Male Sprague-Dawley rats (7 weeks of age) were divided into 3 groups according to diet composition: standard chow (SD; 12,5% kcal as fat), high-fat (HF; 42% kcal as fat), and food cycles (FC) consisting of 10-day alternations between HF and SD diets beginning with the high-fat diet. Rats in each of these 3 groups were sacrificed after 10, 30, and 50 days (n = 10 rats/sub-groups). Energy intake, body weight, liver and muscle relative weights were not significantly (P > 0.05) different between FC- and HF-fed rats. Using the total energy intake for the 50-day period, it was calculated that approximately 30% less calories as fat was ingested in the FC- compared to the HF-fed rats. In spite of this, liver lipid infiltration as well as fat accretion in abdominal adipose tissues were increased (P < 0.01) similarly in FC- and HF-fed rats. Plasma FFA and insulin levels depicted strong tendencies (P < 0.07) to be higher in FC- than in continuous HF-fed rats at the end of the 50-day period. These results indicate that, despite a 30% reduction in ingested lipids, alternations of HF with normal chow diet compared to the continuous hyperlipidic diet caused the same level of infiltration of lipids in the liver and in the abdominal adipose tissues and, to a certain extent, may even result in a larger deterioration of the metabolic profile.