The aim of this study is to examine the effect of 4 weeks of low intensity physical activity program on thyroid hormone levels in obese and overweight boys. A total of 27 boys in the 12-14 age range; obese group 12 and overweight group 15 were divided into two groups. Children who participated in the study during the 4 weeks 3 days a week, games and sporting selected time period of 60 minutes a day walking program applied increasingly. TSH, T3 and T4 levels were determined in blood samples taken at rest 1 day before and one day after the 4 week training program. In the statistical analysis of the data obtained in the study, SPSS package program SPSS 22.0 statistical program (SPSS Inc., Chicago, Illinois, ABD) was used. Paired Samples T tests were used to analyze the difference between the Independent Samples T and the pre-test and post-test of the groups in the comparison of the binary groups. At the end of the study, body weight and T3 values of obese subjects (n = 12) and body weight, BMI and T3 values of overweight group were found to be significantly different between pre-test and post-test (p <0.05). In the analysis of pre-test and post-test differences of measured characteristics of obese and overweight subjects, no significant difference was found (p>0,05). As a result; of obese and overweight boys in the 12-14 age range in the 4-week low intensity physical activity program it can be said to cause changes in thyroid hormone levels.