The 2003–2004 US National Health and Nutrition Examination Survey of 3958 children and adolescents aged 2 to 19 years found that 33.6% of children had a ≥85th percentile BMI [10
]. The prevalence of OW/OB in this cohort of Argentinean children aged 5 to 13 years (34.6%) was very similar to the alarming and increasing rate of OB among children in the United States. Different studies have documented the increasing prevalence of OW/OB among adults and children in many countries throughout the world [11
]. Similar results were found in a recent school study in Buenos Aires, Argentina [4
]. Only 1.5% of the children were underweight. Even if low income populations in South America showed an association between stunting and OW/OB in children [14
], this study did not find this association. This finding could be due to their lifestyles and also because meat is very cheap in Buenos Aires and even low socioeconomic class can eat meat.
In this sample, OW/OB in children was associated with skipping breakfast, increased television viewing time, drinking sweet beverages, and maternal BMI. These observations highlight the importance that lifestyle behaviors play in the childhood obesity epidemic. The reported intake of healthy foods was extremely low in this survey.
Fruits and vegetables have been promoted for the prevention of childhood OB because of their low energy density, high fiber content, and satiety value. Two studies reported that fruit consumption was associated inversely with weight status in children, [15
] but a relationship with vegetable intake was not apparent. Consistent with this survey, several studies found no association between fruit and vegetable intake and childhood OB [17
]. Only 2.1% of the children in this study ate 5 or more portions of fruits and vegetables by day. This could be due to sample size, or some vegetables typically were consumed with fat added during preparation, or just reflect the low consumption in our sample.
At the same time, most of the children reported drinking sweet beverages more than once per day. Consumption of sugar-sweetened beverages may be a key contributor to the epidemic of OW/OB, because these beverages have high added sugar content, low satiety, and incomplete compensation of total energy [21
]. We found as well, in the regression analysis a significant association between sweet drinks consumption and OW/OB children.
Several studies have shown that skipping breakfast decreased the nutritional quality of the diets of children [22
]. Evidence supports the view that OB children are more likely to skip breakfast than their leaner counterparts [15
]. OB children also have been reported to eat smaller breakfasts than their non-obese peers [24
]. We did observe, as well, a significant association among skipping breakfast habits, and OW/OB. The strength of the evidence is somewhat limited, however, because what constitutes a normal breakfast has not been defined consistently [24
In the present study we observed high prevalence rates of sedentary behaviors and there was a strong trend for increased OW/OB with increased TV viewing time. These results support the growing body of evidence implicating television viewing as a major factor in childhood OB [25
]. Several mechanisms have been suggested that link television viewing with OW/OB children. These include an increased dietary intake from eating during viewing or from the effects of food advertising, decreased energy expenditure during viewing, and reduced energy expenditure from television viewing displacing physical activity. [29
]. Watching TV during meals is associated with increased frequency of poor food choices and decreased frequency of good choices [31
]. Consistent with these studies, we found that children watching more than two hours of TV a day were significantly more likely to be higher consumers of sweet drinks.
OB is commonly familial [33
]. Parental OB greatly increases the risk of a child becoming obese [35
]. An OW school-aged child with an obese parent has over a 70% chance of being OB in young adulthood. [36
]. Consistent with these studies, there was a higher prevalence of OW/OB in children with OW/OB mothers. Multiple regression analysis also showed that mothers' BMI was associated with their child's OW/OB. These findings suggest that mother's OW/OB plays a critical role in their children's weight.
Several limitations of this study should be acknowledged. First, it was a cross sectional study and therefore, we were unable to draw conclusions about causation and make observations over time. Nonetheless, appropriate analysis of cross-sectional data is a valuable initial step in identifying associations between behaviors and OW/OB. Second, the use of the information about calorie intake was not used because it was considered unreliable due to the low parental educational level. Despite these limitations inherent to using reported behavioral data, we still found associations among OW/OB and lifestyle behaviors that were consistent, strong, and in the expected direction. Third, the sample was not randomly selected; however, measures of BMI and waist circumference were comparable to those reported in other elementary school studies in Buenos Aires [4
]. Fourth; the reason why a higher number of schools were not included was due to economic limitations. Lastly; as the prevalence of obesity was higher than 10%, OR by logistic regression analysis could overestimate the risk.
The strengths of our study included our school sample, which was more likely to represent the general population of school children, the good response rate of the children, and the use of regression models and simultaneous adjustments of confounding variables, such as physical activity and the intake of other food groups, in the association of lifestyle behaviors with OW/OB.