BACKGROUND: Obesity is a worldwide public health problem associated with cognitive and mental health problems in both humans and rats. Studies assessing the effect of fiber supplementation on behavioral deficits and oxidative stress caused by high-fat diet (HFD) consumption in female rats are still scarce. We hypothesized that HFD consumption would lead to anxiety-related behavior and hepatic oxidative stress and that inulin would protect against these changes. We analyzed the impact of HFD-induced obesity combined with fiber supplementation (inulin) on anxiety-related defensive behavior and hepatic oxidative stress. RESULTS: Female rats were fed a high-fat diet (HFD; 45%) for nine weeks to induce obesity. The administration of inulin was found to decrease the adiposity index in both the control and obese groups. The consumption of a HFD combined with inulin supplementation resulted in a reduction in both CAT activity and carbonylated protein levels, leading to a shift in the hepatic redox balance. Interestingly, the behavioral data were conflicting. Specifically, animals that consumed a high-fat diet and received inulin showed signs of impaired learning and memory caused by obesity. The HFD did not impact anxiety-related behaviors in the female rats. However, inulin appears to have an anxiolytic effect, in the ETM, when associated with the HFD. On the other hand, inulin appears to have affected the locomotor activity in the HFD in both open field and light-dark box. CONCLUSION: Our results show that consumption of a HFD induced obesity in female rats, similar to males. However, HFD consumption did not cause a consistent increase in anxiety-related behaviors in female Wistar rats. Treatment with inulin at the dosage used did not exert consistent changes on the behavior of the animals, but attenuated the abdominal WAT expansion and the hepatic redox imbalance elicited by high-fat diet-induced obesity.