The present study evaluated the association of SB, PA, and weight status among the Yazd students aged 12–16 years before the COVID-19. The current findings were shown the high prevalence of SB, ST, overweight or obesity, abdominal obesity, and physical inactivity among the Yazd students. Gholami and et al.(14) observed a 31.5 % of prevalence of overweight and obesity among the Yazd students aged 9–13 years. The present findings showed a higher prevalence of overweight, obesity, and low PA rather than the study conducted by Gholami.
However, all normal-weight students spent less time on the school days and all week’s ST, HT, and SB than overweight or obese ones, they spent a little more time on the weekends’ HT. Moreover, overweight or obese students showed an increment of weekends’ SB but it was no significant. The higher chance of overweight or obesity among Yazd students was related to the younger age, high energy intake, smaller family size, no access to the yard, the commuting to school by motor vehicles, higher school days’ HT, the school days’ SB, and the weekends’ HT and lack of moderate and high PA levels. A lower school days’ ST was inversely related to overweight or obesity. The boy students with overweight or obesity spent more time on the school days and week’s ST, HT, and SB and the weekends’ ST than the normal-weight boys. Moreover, higher chances of overweight or obesity were related to the younger age, high energy intake, smaller family size, no access to the yard, the quartile 2 of the school days’ SB, and lack of moderate and high PA levels. In the girl students, there was a higher risk of overweight or obesity for high energy intake, no access to the yard, spending more time on the school days’ HT and the weekends’ HT, the quartile 2 of the week’s ST and lack of the high PA levels.
However, Kelishadi et al.(8) showed physical inactivity ≥ 2 times in the girl than boy Iranian students aged 13–18 y, the analysis of total students were near the results of the present study. Moreover, they reported a lower prevalence of general and abdominal obesity than Yazd students. The results of two published studies (2020) by Amiri et al. (19) and Khazaei et al. (20) presented an increasing trend of low PA among Iranian adolescents across urban and rural areas and obesity among Iranian children and adolescents, respectively.
In agreement with our results, Kelishadi et al. (5) illustrated there was a higher BMI among physically inactive Iranian children and adolescents. But their findings of the positive association between watching TV or using a PC ≥ 2 hours/day and PA were the opposite of the current study. The results of a meta-analysis (2019) showed that ST especially watching TV and using PC ≥ 2 h/day was related to overweight or obesity among children and adolescents (9). In accordance with our results, Omorou et al. presented that overweight and obesity in French adolescents were related to SB rather than PA (12). Some SB (watching TV, Video/DVD, and Homework ≥ 2 h/day), insufficient PA, and high-calorie foods related to a high risk of overweight among Sri Lanka students aged 14–15 y (5). However, their results were similar to the current study, there was not any data for the school days or weekends.
As our results showed, there was a positive relationship between younger age and smaller family size with overweight or obesity in the boys and all the students but no significant difference was found between family size and age with weight status among the girls. In compliance with our results, Mozafarian et al.(7) illustrated that there was a negative association between the children number and spending time for SB. After adjusted BMI effects, younger age was related to insufficient PA in Brazilian boys (14-18y) but not in the girls (10).
Among Irish students aged 8–11 y, a higher risk of overweight or obesity was linked to the low PA and a high SB time on all week, weekdays, and weekends. Independent of total SB time, a high risk of overweight or obesity was related to spent lower time at the PA (21). Our results showed a higher chance of overweight or obesity among the students is relevant to more time on the school days’ SB, HT, and ST and weekends’ HT. However, independent of PA, an increased chance of overweight or obesity was associated with ST but not total SB time among Irish students aged 8–11 years (21). In line with the present results, Górnicka et al.(11) illustrated that higher PA reverses the trend of overweight.
Gholami et al. presented that the Yazd students who used motor vehicles had a higher BMI. Their results were similar to ours. However, they reported that 64.5% of Yazd students (9–13 years) commuted to the school by walking or biking (14), the present study showed 45.3% of the Yazd students (12–16 years) used the active way of commuting to the school. It may emanate from that the choice of high quality and facilities school has higher importance rather than near distance for the parents (14). Attention to active transport is so important due to its role in expending a large amount of energy (14). As the previous studies and the present study emphasized, the risk factors of obesity, were varied based on age, race, country, SES, parents’ education levels, and gender (11).
The limitations of our study were a) using self-reported data on dietary intake, ST, SB and PA (however, the present questionnaire used in previous studies (7, 8, 11, 15, 22)), b) the content of dietary intake were not assessed for the current study, the interpretation should be done caution given that this is a cross-sectional study, c) the consideration of more confounder factors including the quality and quantity of dietary intake, sleep habits, socioeconomic status (SES), parent history of overweight or obesity, and etc., d) the lack of the data for all year (the data was collected at a particular point of time (only for an academic year), and finally SB was assessed for the activities out of the school time.
Our study had some strong aspects including 1) sample size was nearly large; 2) data were collected from both gender; 3) the analysis was performed based on both genders as well as the weekdays and weekend apart from all week; 4) the evaluation of the relationship between overweight or obesity with daily energy intake, PA and the times spent on ST, HT, and SB; 5) the analysis for abdominal obesity was performed (due to the similarity to the present results did not show); 6) the presence of the qualified and same assessors while filling in the questionnaire allowed adolescents to clarify uncertainties and reduce the biases; and finally, the data for ST and SB was comprehensive.
According to the current and previous findings (3–7, 11, 13, 15), it seems to be necessary that policymakers should take the measures to modify lifestyles to reduce the prevalence of overweight or obesity during adolescence.
It was suggested performing a large and comprehensive study due to collecting the data for all year (academic and nonacademic year), as well as at the new situation with the COVID-19 (the presence of quarantine, mandatory online education, and the more accessible to cyberspace) and evaluating more risk factors of obesity in the different region of the country given that the risk factors of overweight or obesity were too wide (11).