The association between screen time (ST) , including that for smartphones, and overweight/obesity (OW/OB) in children was examined separately for boys and girls, considering the influence of lifestyle factors including diet, physical activity, and sleep time. A cross-sectional study was conducted in 2242 Japanese children (1278 girls) aged 10-14 years. OW/OB was defined by the International Obesity Task Force. Logistic regression analysis showed that only for girls, total ST (≥4h) , smartphone ST (≥3h) and non-smartphone ST (≥2h) were all independently and significantly associated with overweight/obesity compared to <2h total ST, non-use of smartphones, and <1h non-smartphone ST. In girls with total ST ≥5h or <4h or smartphone ST <2h, the association between ST and OW/OB was not affected by physical activity or sleep time. On the other hand, when total ST was 4-5h or smartphone ST was ≥2h, the significant association with OW/OB disappeared when physical activity was ≥60 min/day and sleep time was ≥8.5h. In addition, none of these associations were significant in boys.

In Japanese girls, smartphone ST, non-smartphone ST, and total ST were all significantly associated with OW/OB. To avoid OW/OB, it is suggested to keep smartphone ST, non-smartphone ST, and total ST to <3h, <2h, and <4h, respectively, and to engage in sufficient physical activity and sleep time.


K. Fujihara: None. S.Y. Morikawa: None. H. Ishiguro: None. M.H. Yamada: None. C. Horikawa: None. Y. Ogawa: None. H. Sone: Research Support; Astellas Pharma Inc., Eisai Co., Ltd., Kyowa Kirin Co., Ltd., Novo Nordisk, Ono Pharmaceutical Co., Ltd., Taisho Pharmaceutical Holdings Co., Ltd., Takeda Pharmaceutical Company Limited.

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