Intermittent fasting (IF) is a beneficial dietary treatment for obesity which improves metabolic health independent of weight loss. A major co-morbidity of diabetes is non-alcoholic fatty liver disease (NAFLD) where the accumulation of liver fat leads to fibrosis and reduced liver function. The risk for NAFLD is higher in men and post-menopausal women which suggests sex hormone signalling plays a critical role in NAFLD prevention. Recently, we completed the first proteomic analysis of IF in male and female mice, which enabled the discovery of a sexually dimorphic response to IF in the liver. This analysis was completed using capillary flow DIA analysis over 1h gradients using DIA-NN as the search engine. This analysis consistently identified >4,500 proteins across the cohort and statistical analysis with a two-way ANOVA showed that IF and not gender had the strongest effect on protein abundance. Interestingly, females had increased interferon-alpha (IFNα) signalling after IF and increased abundance of downstream IFNα targets, whereas males had minimal change. IFNα signalling has previously been shown to reduce fibrosis within the liver. To validate these findings, we applied IF to castrated mice and repeated the proteomic analysis, which showed testosterone signalling represses IFNα pathway induction in the liver after IF. Conversely, analysis of liver tissue from ovariectomised mice did not diminish this IFNα response, suggesting the sexual dimorphism arises from testosterone induced suppression via the androgen receptor. Currently, we are performing additional animal experiments to examine this effect across a variety of mouse strains and to test the effect of IFNα receptor (IFNAR1) knockout on the IF response in females. Further questions remain about the direct protective efficacy of IF against liver fibrosis that we aim to test in a mouse liver fibrosis model. This works highlights an interesting link between IF and NAFLD treatment and an opportunity to develop new dietary treatment strategies for NAFLD.