In the present study, we examined the associations between several lifestyle factors and overweight/obesity or abdominal obesity in Saudi adolescents aged 14–19

years, who were randomly selected from three major cities in Saudi Arabia. The main findings of this study are that males (compared with females) and adolescents in private (compared with public) schools have higher odds of being overweight or obese. In addition, logistic regression analysis indicated that Saudi adolescents had higher odds of being overweight/obese or abdominally obese if they less frequently engaged in vigorous physical activity, consumed breakfast or vegetables on

<

3

days per week, and consumed sugar-sweetened beverages for 3–4

days per week or

<

3

days per week.
The recommendations for the prevention and management of childhood obesity emphasize lifestyle modification, including daily moderate to vigorous physical activity, reducing television viewing and computer use, and avoiding unhealthy dietary habits, such as frequent consumption of fast foods, sugar-sweetened beverages, skipping breakfast and infrequent consumption of fruits and vegetables [
10].
The current study showed that male adolescents had higher odds to be obese compared with their female peers. It is worth noting that the combined prevalence of overweight and obesity in many local and regional studies is higher in males than in females [
2]. This is similar to the combined overweight and obesity profile of males and females among white American adolescents but opposite to that in black American adolescents [
41]. However, the sex differences in rates of obesity among adolescents are generally small and inconsistent [
42].
The findings of this study indicate that adolescents in private (compared with public) schools have higher odds of being overweight or obese. Adolescents in private schools usually come from families with higher socioeconomic status. At private schools, they may also have less restriction on food and snack choices compared with those in public schools. It is worth noting that studies on socioeconomic status and obesity suggest that the rate of obesity is higher among low income groups in developed countries, and in high income groups in developing countries [
1,
43]. This notion is supported by the present findings.
The finding that overweight/obesity was associated with lower levels of physical activity highlights the important role that physical activity, particularly vigorous activity, plays in preventing adolescent obesity. The present findings are consistent with the growing evidence showing that physical inactivity is a leading factor in obesity during childhood and adolescence [
22,
23,
44-
46]. In addition, insufficient vigorous physical activity was shown to be a risk factor for higher BMI in adolescent boys and girls in the United States [
47]. Findings from a cross-sectional survey of adolescents aged 10–16

years from 34 countries demonstrated that physical activity levels were lower and television viewing times were higher in overweight compared to normal weight individuals [
44]. An earlier study in Saudi Arabia [
31] also showed that inadequate physical activity was associated with obesity in adolescents (OR 1.6; 95% CI 1.01–2.62). Similarly, a lack of exercise was a significant risk factor for obesity among adolescents from southwestern Saudi Arabia (aOR 1.35; 95% CI 1.06–1.94) [
29]. Our finding that vigorous-intensity physical activity was inversely associated with adolescent obesity is also extensively supported by the literature. For example, Patrick et al. [
47] studied a group of adolescents aged 11–15

years from the United States and found a significant association between overweight and vigorous-intensity physical activity but not with moderate-intensity physical activity. Furthermore, compared with moderate-intensity physical activity, a stronger negative association was reported between vigorous-intensity physical activity and total and central body fat in Spanish adolescents [
48]. In addition, a review of the influence of physical activity on adiposity among 5–18

year olds concluded that a reduction in adiposity and an increase in aerobic capacity were observed when more time was spent on performing vigorous-intensity physical activity [
49].
Excessive screen viewing in adolescence appears to be related to an unfavorable cardiovascular risk profile [
50]. It is also believed that sedentary behaviors are associated with adverse health outcomes in a way that seems to be different from those attributed to the lack of physical activity [
51]. In the current study, total screen viewing time was not associated with overweight or obesity. This finding is similar to those of several earlier studies that reported very weak [
27] or no associations between screen viewing time and obesity [
52]. However, other studies have reported significant associations between screen viewing time and obesity in children and adolescents [
53-
55]. In fact, some studies concluded that sedentary behaviors, such as television viewing, may be more important predictors of obesity indices in children than are physical activity behaviors [
21]. However, ethnic and cultural factors may, at least partly, influence the associations between screen viewing time and obesity [
53].
Some studies have suggested that there is an interaction effect between screen viewing time and physical activity that may influence the associations between obesity and sedentary behaviors. For example, Eisenman et al. [
56] studied the combined effects of physical activity and television viewing on the risk of overweight and found that girls with high television viewing time and low physical activity had the highest odds of being overweight (OR 3.11). Meanwhile Dupuy et al. [
23] reported that, in French adolescents aged 11–15

years who engaged in

≥

60

min of moderate to vigorous physical activity on

≥

5

days per week, television viewing was not associated with overweight, implying that high levels of physical activity may compensate for the negative effects of TV viewing. In the current study, we did not find a similar phenomenon nor was there an interaction between sedentary behavior and physical activity relative to obesity status. Furthermore, another recent study has shown that television viewing (sedentary activity) and physical activity appear to be separate entities that are independently associated with metabolic risk [
54].
It appears that not all screen-based activities have equivalent associations with childhood obesity. Indeed, video games and computer use do not confer such high risk for obesity when compared with television viewing [
57]. Research conducted on Australian adolescents has shown that computer use and video games were not significant risk factors for overweight or obesity [
27]. However, in Brazilian adolescents, overweight was associated with more computer use [
20]. In the present study, we did not find any significant differences between television viewing time or computer/video games use in relation to overweight or obesity; therefore, we combined both behaviors into a single variable.
Among all of the dietary habits assessed in the present study, overweight and obesity status was significantly associated with less frequent consumption of breakfast and sugar-sweetened drinks. In addition, reduced intake of vegetables was associated with increased odds of abdominal obesity. Other than the association with less frequent intake of sugar-sweetened drinks, our findings agree with those of many other studies. Indeed, skipping breakfast is a strong predictor of overweight and obesity in children and adolescents from many countries [
15,
20,
58,
59]. However, among 11–16-year-old Canadians, there was no clear association between dietary habits and measures of overweight and obesity [
55]. The World Health Organization’s Global Strategy for Diet and Physical Activity recommend limiting energy intake from fats, reducing the intake of free sugars, and increasing fruit and vegetable consumption [
60].
Surprisingly, the present study found significant inverse associations between the frequency of consuming sugar-sweetened drinks and measures of overall and abdominal obesity. This finding differs from those of many other studies. In a multivariate regression model, waist circumference was positively correlated with self-reported sugar-sweetened beverage intake among adolescent males [
28]. Moreover, the consumption of sugar-sweetened drinks was found to be associated with obesity in children [
61]. In a longitudinal study of non-obese adolescent girls, soda beverages were the only energy-dense snack food to be significantly associated with BMI z-scores over the 10-year study [
62]. It has been suggested that sugar-sweetened beverages in liquid form could lead to increased caloric intake because they are less satiating than solid foods containing a similar energy content [
61,
62]. Our finding of the lower intake of sugar-sweetened beverages in overweight/obese subjects is difficult to interpret. It is possible, however, that the overweight/obese adolescents underestimated their intake of sugar-sweetened beverages and sweets. Another explanation is that overweight/obese adolescents might have been dieting and were switching to reduced-calorie beverages. In a 5-year longitudinal study, Vanselow et al. [
26] found no association between sweetened beverage consumption and adolescent weight gain during the 5-year study. However, they did observe a positive association between low-caloric soft drinks and weight gain [
26]. In our study, we did not assess the intake of reduced-calorie beverages.
A recent systematic review on the role of fruit and vegetable intake and obesity in children and adults concluded that increased fruit and vegetable consumption contributed to reduced adiposity among overweight or obese adults, but not among children, in experimental studies [
63]. On the other hand, longitudinal studies of overweight adults showed marked associations between increased consumption of fruits and vegetables, and slower weight gain, but only one half of the children longitudinal studies indicated significant inverse associations between fruit and vegetable intake and obesity [
63]. In the current study, we found a significant association between reduced vegetable, but not fruit, intake and increased odds of having abdominal obesity. The mechanism by which fruit and vegetable intake may prevent obesity is not fully understood, but could be related to the clustering effect of healthy habits. In our study, vegetable intake was correlated with frequency of breakfast consumption (
r
=

0.24,
p
<

0.01) and physical activity levels (
r
=

0.15,
p
<

0.01). In another study in Saudi adolescents, exercise was also positively correlated with fruit and vegetable intake [
28].
Lifestyle-related factors, such as dietary habits, sedentary behavior and physical activity, all play an important role in creating an obesogenic environment. In Saudi Arabia, as well as other countries in the Eastern Mediterranean region, the pattern of food consumption pattern has changed enormously over the past four decades. During this time, the intake of animal products and refined sugar has increased while the intake of fruit and vegetables and complex carbohydrates has decreased [
64]. In addition, Western calorie-dense fast foods are increasingly available and consumed by the young generation in this region. In the present study, there was no significant association between the frequency of fast food intake and obesity. In logistic regression models, fast food intake, along with several other variables, was highly correlated with other independent lifestyle factors, which were excluded from the logistic regression because they were considered redundant. However, the portion size of fast foods, which was not accounted for in this study, may be a confounding factor and could influence the association between the frequency of fast food consumption and obesity. Elsewhere, it was shown that fast food consumption markedly increased while frequency of skipping breakfast decreased during the transition from adolescence to adulthood, and both dietary behaviors were associated with weight gain during the same period [
65]. Among Chinese children and adolescents, frequent consumption of snacks and Western fast food were associated with overweight and obesity [
66].
The findings of the present study should be interpreted in light of its strengths and limitations. The main strength of our study is the large, representative and geographically diverse sample. We also used two indicators of obesity, namely cut-offs for BMI and WHtR. In addition, the physical activity questionnaire used in this study is valid and reliable. However, we must also acknowledge some of the limitations of the present study. The potential for recall bias in the frequency of physical activity, sedentary behaviors and dietary habits cannot be completely excluded. In addition, this was a cross-sectional study, which means we cannot infer causality from the current findings. In addition, the food frequency questionnaire did not account for portion size, which may influence the associations between dietary habits and measures of obesity.