Overview: Recently, we found that obese mothers cause NAFLD in their offspring through an unknown mechanism.The biological clock is a transcriptional mechanism responsible for synchronizing physiological and behavioral processes in rest/activity and energy utilization in a 24-hour cyclic rhythm coordinating circadian rhythms from day to night. Alterations in circadian rhythms can have profound effects on central and peripheral metabolic pathways. Here, we hypothesized that central alterations in rhythms act on a clock mechanism centered in the liver, leading to the development of NAFLD in offspring. METHODS: C57BL6 female mice were fed standard or (OD) during the first 6 weeks of pregnancy, throughout gestation, and during lactation. A litter of 8 pups was standardized and the offspring were then given a standard weaning or obesogenic diet and divided into four groups. Studies were conducted at 12:12 hr day-night alternating with 4 hr intervals over a 6-month period. Exercise behavior was evaluated. Blood and tissue were retained for biochemical and histological analysis of liver phenotype and expression of typical clock genes. RESULTS: Obese dams and offspring mice on a post-weaning obesogenic diet (OffOb-OD) had a significantly higher incidence of NAFLD compared to those on postnatal exposure (OffCon-OD) or control (Off-Con-SC), as evidenced by elevated ALT (p<0.001), NAFLD inflammatory activity score (p<0.01) and hepatic glycerol triglycerides (p < 0.001). 10-15% lower nocturnal locomotor behavioral activity was observed in the OffOb-OD and OffCON-OD groups compared with a significant decrease in total daily viability (p<0.01). Typical clock gene expression was observed in the liver, although obese female rat offspring resulted in CLOCK,BMAL1 and Per2 mRNA transcriptional phase overshoot (p<0.01) as well as CLOCK bidirectional rhythm patterns (p<0.05). MO-independent OD resulted in a 1.1-1.8 hr delay in REV-ERB-α timing (p<0.01). Upregulation of BMAL1 and Cry2 mRNA transcripts was found in mice developing NAFLD (p<0.05). However, higher expression levels of CLOCK,BMAL1, REV-ERB-α and Cry1 baseline constitutive phenotypes were found by cosine analysis compared to controls (p<0.05). In addition, hepatic pro-inflammatory and fibrotic mediators, IL-6, TNF-α and α-SMA, TGF-β and collagen rhythms were all disturbed in the OffOb-OD group (p<0.05). CONCLUSION: Obese mothers and high caloric feeding after birth greatly disrupt the circulation of circadian rhythms of liver molecules in the offspring. Theoretically, this may be related to the development of hepatic fibrosis in NAFLD.