The aim of the present study is to evaluate whether circadian locomotor activity, and the daily profile of plasma parameters related to metabolic syndrome (nutrients: glucose and triacylglycerides, and hormones: insulin and leptin), differ between male and female Neotomodon alstoni mice, both lean and obese. Young adult animals were captured in the field and kept at the laboratory animal facility. After 6 to 7 months feeding the animals ad libitum with a regular diet for laboratory rodents, 50-60% of mice became obese. Comparisons between sexes indicated that lean females were more active than males; however obese females reduced their nocturnal activity either in LD or DD, and advanced the phase of their activity-onset with respect to lights off. No differences in food intake between lean and obese mice, either during the day or night, were observed. Daily profiles of metabolic syndrome-related plasma parameters showed differences between sexes, and obesity was associated with increased values, especially leptin (500% in females and 273% in males) and insulin (150% in both females and males), as compared with lean mice. Our results indicate that lean mice display behavioral and endocrine differences between sexes, and obesity affects the parameters tested in a sex-dependent manner. The aforementioned leads us to propose N. alstoni, studied in captivity, could be an interesting model for the study of sex differences in the effects of obesity.