[ABSTRAK
Obesitas anak adalah kondisi ketika Indeks Massa Tubuh menurut Umur (IMT/U) anak > 2SD yang berdampak pada status kesehatannya sekarang maupun nanti. Kejadian obesitas pada anak usia 5-15 tahun di Indonesia sebesar 8,3%, sedangkan Jawa Barat yakni 7,4% pada anak laki-laki dan 4,6% pada anak perempuan. Penelitian pre-eksperimental ini bertujuan untuk menurunkan IMT/U anak obesitas melalui peningkatan aktivitas fisik berbasis sekolah, dilakukan selama 4 minggu dengan melibatkan 25 responden yang mengalami obesitas. Analisis data menggunakan Uji T Berpasangan (paired t-test), dimana rata-rata penurunan IMT/U yang terjadi sebesar 0,20 poin dengan penurunan berat badan sebesar 0,35 kg. Pada analisis bivariat ditemukan hubungan signifikan antara penurunan IMT/U anak obesitas dengan peningkatan aktivitas fisik (p=0,000) dengan penurunan terbesar pada minggu ketiga setelah intervensi. Penelitian ini membuktikan bahwa dengan meningkatan aktivitas fisik selama 4 minggu di sekolah dapat menurunkan IMT/U anak obesitas. Disarankan kepada pihak sekolah menambah durasi mata pelajaran olahraga dan membudayakan kembali senam disekolah.

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ABSTRACT
Childhood obesity is a condition when a children?s body mass index (BMI)-to age reached >2 in z-score, which will affect the health status, present or the future. Childhood obesity prevalence for children aged 5-15 in Indonesia is 8,3%, meanwhile in East Jawa Province are 7,4% for the boys and 4,6% for the girls. This pre-experimental research?s goal is to reduce the obese child?s BMI-to age by increasing the school-based physical activity program for 4-weeks with 25 obese children. The paired t-test uses to analyze the data where BMI-to age reduced for 0,20 point with 0,4 kg weight lost. The bivariate analysis shows a significant association between the BMI-to age reducement by increasing physical activity (p=0,000). It is proven that by increasing school-based physical activity for 4 weeks is able to reduce obese child?s BMI-to age. Suggested for the school to give more time for physical activity education and re-using chalisthenics as the school?s culture.;Childhood obesity is a condition when a children’s body mass index (BMI)-to age reached >2 in z-score, which will affect the health status, present or the future. Childhood obesity prevalence for children aged 5-15 in Indonesia is 8,3%, meanwhile in East Jawa Province are 7,4% for the boys and 4,6% for the girls. This pre-experimental research’s goal is to reduce the obese child’s BMI-to age by increasing the school-based physical activity program for 4-weeks with 25 obese children. The paired t-test uses to analyze the data where BMI-to age reduced for 0,20 point with 0,4 kg weight lost. The bivariate analysis shows a significant association between the BMI-to age reducement by increasing physical activity (p=0,000). It is proven that by increasing school-based physical activity for 4 weeks is able to reduce obese child’s BMI-to age. Suggested for the school to give more time for physical activity education and re-using chalisthenics as the school’s culture., Childhood obesity is a condition when a children’s body mass index (BMI)-to age reached >2 in z-score, which will affect the health status, present or the future. Childhood obesity prevalence for children aged 5-15 in Indonesia is 8,3%, meanwhile in East Jawa Province are 7,4% for the boys and 4,6% for the girls. This pre-experimental research’s goal is to reduce the obese child’s BMI-to age by increasing the school-based physical activity program for 4-weeks with 25 obese children. The paired t-test uses to analyze the data where BMI-to age reduced for 0,20 point with 0,4 kg weight lost. The bivariate analysis shows a significant association between the BMI-to age reducement by increasing physical activity (p=0,000). It is proven that by increasing school-based physical activity for 4 weeks is able to reduce obese child’s BMI-to age. Suggested for the school to give more time for physical activity education and re-using chalisthenics as the school’s culture.]