The purpose of this study was to examine resting metabolic rate (RMR) and thyroid hormonal (TSH, $T_3$, and $T_4$) changes following weight loss by diet with regular exercise in obese women. The subjects of the present study were 7 women who were above 30% body fat. The subjects arrived into the laboratory in the morning after 12 hour overnight fasting. All subjects measured RMR, % body fat, and fat free mass at weight loss program start time, after 4 weeks and after 8 weeks. All the RMR values were expressed as absolute value (kcal/day), absolute value/FFM (kcal/day/FFM), and absolute value/BSA (kcal/$m^2$/hr), and were calculated predicted RMR value minus actual RMR value. Also, correlation of blood thyroid hormonal (TSH, $T_3$, and $T_4$) secretion and RMR were analyzed. There were significant differences in weight, % body fat, and BSA following diet with exercise (p<0.05). Also, there was a difference between predicted RMR and actual RMR value following weight loss (p<0.05). We also examined the hormonal changes according to weight loss. After weight loss, the level of TSH and $T_4$ were higher than before. But there were no significant differences. Also, the level of $T_3$ was lower than rather before but there was no significant difference. Among the anthropometric factors, FFM was highly correlated (r=0.761) with actual RMR value before weight loss. Also, there was a correlation (r=0.771) with actual RMR value after weight loss. Therefore, actual RMR expressed as FFM increased in weight loss program by diet with exercise. There were no changes in the level of thyroid hormonal TSH and $T_4$.