Objective To investigate the role of SIRT1 in the effect of intermittent fasting on mitochondrial function and inflammation in white adipose tissue(WAT)of obese mice induced by high-fat diet. Methods Male C57BL/6 mice aged 5-6 weeks were randomly divided into the control diet (CD)group (n = 5), high‐fat diet (HFD)group (n = 5)and high-fat diet intermittent fasting (HFD-IF, alternate-day fasting 24 h)group (n = 5)and fed for 12 weeks. The pathological changes of WAT were observed by HE staining. The expression levels of SIRT1, p-AMPK, FOXO1 and mitochondrial function, inflammation-related genes in WAT of each group were detected. AAV-shSIRT1 virus was delivered by tail-vein injection into mice to knockdown SIRT1. HFD and HFD-IF were given. The parameters above were determined. Results HE staining indicated that the adipose cell volume was decreased in the HFD-IF group. Western blot showed that the expression levels of SIRT1, p-AMPK and FOXO1 in adipose tissues were significantly down-regulated in the HFD mice (all P < 0.05), which were significantly up-regulated after intermittent fasting (all P < 0.05). qPCR revealed that the expression levels of mitochondrial functional genes, including Tfam, Nrf1 and Pgc-1a were dramatically down-regulated in the HFD group (all P < 0.001), whereas those of inflammatory markers, such as TNF-α, MCP-1 and F4/80, was significantly up-regulated (all P < 0.01). After intermittent fasting, the expression levels of genes related to mitochondrial function were up-regulated (all P < 0.05), whereas those of inflammatory markers were down-regulated (all P < 0.05). After knockdown of SIRT1, the trend of up-regulating or down-regulating the expression levels of these parameters was weakened or even absent in the HFD-IF group (all P < 0.05). Conclusion SIRT1 mediates intermittent fasting in improving high-fat diet-induced obesity via ameliorating adipose tissue mitochondrial function and inflammation. [ABSTRACT FROM AUTHOR]