Information about seasonality in the measurement of diet-induced thermogenesis (DIT) is important for understanding the intra-individual variability of DIT and the contribution of DIT on weight regulation. In this study, the seasonal change of DIT in autumn and winter were investigated for young women (N = 14, 18 – 24 yrs). The DITs of subjects were measured in autumn and winter. The DIT, body weight, body mass index (BMI) and percent body fat of each subject were measured on four or more occasions in each season for precision, and the mean value was used as the individual's value for a given season. The mean outdoor temperatures at starting measurement in the morning were 22°C in autumn, and 11°C in winter. The means of body weight, BMI and percent body fat did not change between seasons. DIT (%) significantly declined from autumn to winter (p < 0.05, Paired t-test). For DIT curve (the increase of postprandial energy expenditure during 300 min after meal), significant main effect of season was observed (ANOVA, p < 0.05, autumn > winter).

　In conclusion, there is the seasonal effect on DIT measurement; it declines from autumn to winter. The seasonality would be needed to be considered in any future study of DIT.