Overweight and obesity is a growing worldwide epidemic, cited by the World Health Organization as one of the leading public health challenges of the 21st century (1). Overweight and obesity are major risk factors for numerous chronic diseases including diabetes, cardiovascular disease, and cancer; these diseases result in the deaths of about 3.4 million adults each year (2). In particular, overweight and obesity in children and adolescents is significant because of the amount of data citing these conditions as predictors for adult obesity (3).

Once considered the concern of high-income countries, low-income and middle-income countries are quickly beginning to experience the same trends (4). It has also been predicted that the increase in adolescent obesity in the coming years will be 30% higher in low-income and middle-income countries than in the high-income countries (2). Tunisia in particular has seen a rise in overweight and obesity rates in adolescents as a result of the ongoing epidemiologic transition in the country (5). Changes in nutritional habits and improvements in health care delivery have rapidly changed health trends in the country, switching the country’s most common adverse health conditions from infectious diseases to noncommunicable diseases and their risk factors.

To properly combat the rise of overweight and obesity rates, risky behaviors must be modified. In determining these behaviors, many factors (including environmental and genetic factors) must be considered when assessing the cause of excessive weight gain. Despite the complexity of the underlying factors behind overweight and obesity, it is accepted that excess weight results from an imbalance between energy intake and energy expenditure (6). Understanding this imbalance has allowed numerous interventions to observe the importance of nutrition and physical activity in combating the obesity problem in adolescents (1).

Although a significant number of school-based studies look into modifying nutrition and physical activity behaviors to combat the obesity problem in developed countries, only a handful have been conducted in the developing world. In Tunisia, a school-based study on nutrition promotion is the only other known study on the topic (7).

Our study aimed to evaluate the effectiveness of “Schools in Health,” a school-based physical activity and nutritional behavior intervention, in reducing overweight and obesity rates among the schoolchildren of Sousse, Tunisia.

The region of Sousse, covering an area of 2,612 km², is composed of 15 delegations with 655,900 inhabitants estimated in 2013. Food expenditure is the highest expenditure (34.8% of the total). Adolescents are the main group that is moving away from traditional foods to a modern diet, linked to urbanization and increased economic level, which features increased consumption of white bread, dairy products, sugars, added fats, and fruits and decreased consumption of oils, grains, legumes, and vegetables (5).

The questionnaire was delivered to 4,003 schoolchildren for the collection of preintervention data, with a 94.6% response rate. Of those schoolchildren, 2,074 belonged to the control group and 1,929 belonged to the intervention group. In the postintervention examination, 4,275 (92.9% response rate) schoolchildren participated in study, with 2,106 of the participants belonging to the control group and 2,169 belonging to the intervention group. Boys accounted for 50.2% of the intervention group at preintervention assessment, and 48.7% of the participants at postintervention assessment. The 13-or-younger age group was 55.7% of the intervention group at preintervention and 54.7% at postintervention. For the control group, 46.5% of the schoolchildren at preintervention were boys and 47.7% were boys at postintervention. The 13-or-younger age group was 46.8% of the control group at preintervention and 52.7% at postintervention. There was no significant difference in sex or age between the preintervention and postintervention data of the intervention group (P = .35 and P = .53, respectively). In the intervention group, schoolchildren from a low socioeconomic background decreased from 24.7% at preintervention to 19% at postintervention, medium level decreased from 37.1% to 34.9% at postintervention, and high level increased from 38.2% to 46.1% postintervention. In the control group, children in the low socioeconomic level decreased from 24.4% at preintervention to 16.7% postintervention, medium level decreased from 43.1% to 38.1%, and high level increased from 32.5% to 45.2%. The socioeconomic levels of the intervention and control groups were significantly different from the levels of the preintervention and postintervention groups (P < .001).

The percentage of obese schoolchildren also decreased in the intervention group but not significantly while the percentage of obese schoolchildren in the control group increased significantly (P < .001) (Table 1).

Overall, the boys’ weight status improved postintervention more than the girls (Table 1). In the comparison between preintervention data and postintervention data, recommended fruit and vegetable intake improved significantly, from 30.0% to 33.2% postintervention (P = .03) while decreasing significantly in the control group from 40.2% to 35.0% (P = .001) (Table 2). Fried food and fast food intake also decreased in the intervention group but not significantly. There was a significant decrease (P < .001) in schoolchildren who walked or biked to and from school in the control group postintervention but a nonsignificant increase (from 72.2% to 74.0%) in the intervention group. There was a significant decrease (P = .01) in schoolchildren who did the recommended amount of physical activity in the intervention group, dropping from 29.1% to 25.5% postintervention. No significant changes were seen in sedentary behaviors in the intervention group while a significant decrease was observed on Sundays for the control group (P < .001).

The multivariate analysis model, which used a binary logistic regression (Table 3), found a difference between the control group and the intervention group. Sex was included in the analysis for adjustment purposes. In the intervention group, protective factors against excess weight included the intervention effect (OR, 0.84; 95% CI, 0.73–0.97), increased age (OR, 0.91; 95% CI, 0.86–0.97), participation in recommended physical activity (OR, 0.80; 95% CI, 0.68–0.96), and recommended fruit and vegetable intake (OR, 0.84; 95% CI, 0.72–0.99). In contrast, the risk of excess weight increased with walking/biking to school (OR, 1.33; 95% CI, 1.11–1.56), and fast-food intake (OR, 1.18; 95% CI, 1.00–1.38). High socioeconomic level also increased the risk of excess of weight when compared with low socioeconomic level (OR, 1.25; 95% CI, 1.03–1.52).

The aim of this study was to evaluate the effectiveness of a physical activity and nutritional behavior intervention in reducing the overweight and obesity rates of schoolchildren of Sousse, Tunisia. This evaluation of the intervention showed promising progress toward a reduction in overweight and obesity rates in schoolchildren. Through the encouragement of positive lifestyle changes, schoolchildren in the intervention group were able to significantly improve their weight status, leading to a decrease in the overweight categories and an increase in the normal weight category.

The design of this study as a quasi-experimental school-based intervention with a reference group was one of its greatest strengths. The establishment of the program as a component of a larger community-based intervention limits our ability to categorize the intervention as strictly school-based. However, the design allowed for a comprehensive evaluation of the data, and in a developing country like Tunisia, it is a valuable stepping stone for future programs. Regions were selected based on proximity to the research center. Nonrandomization can lead to incomparability of the intervention and control groups. However, in data analysis, we compared only preintervention data with postintervention data and did not compare intervention group data with control group data.

We recognize that a quasi-experimental design cannot ensure that observed changes are the effect of the intervention. However, the intervention program was beneficial for schoolchildren.

The self-assessment questionnaire was another limitation of the program. Although the questionnaire was pretested and administered by professionals, false estimations of diet and physical activity behaviors by the schoolchildren are a possibility. This program also lacked effective environmental change. The occurrence of the Tunisian revolution in 2011 made it difficult for the program to enforce planned policy and infrastructural improvements as they were not considered a priority by schools and policy makers at the time. This program did, however, show the importance of such changes, and future interventions should consider including them in their programs. Findings from this study can be used to show the need for environmental modification, particularly in policy regulation that affects the surrounding the food environment and in decisions about infrastructure in the form of safe physical activity spaces.

Despite reducing the prevalence of overweight, little difference was observed in positive behavioral modifications among the schoolchildren. The most significant improvement was seen in fruit and vegetable intake. Other school-based interventions also encountered a lack of consistent behavioral results (10–12). One intervention in Australia showed inconsistent behavioral outcomes in dietary and physical activity behaviors despite the positive reduction in anthropometric measurements (11). In contrast, numerous other interventions showed positive changes in nutritional and physical activity behaviors but were unable to also show significant decreases in overweight and obesity (12,13). The most successful programs in reducing the prevalence of overweight and obesity were the ones that included some type of environmental change in the intervention (14). These changes included creating school-based gardens, making structural changes to physical activity courses, and making various policy and infrastructural changes (14). One intervention in Germany reduced the risk of overweight in schoolchildren by 31% at postintervention by installing water fountains in the intervention schools (8).

In terms of behavioral change, this intervention was able to show significant improvements in nutritional intake, similar to findings by other school-based studies (10,15). Findings from this study are also consistent in showing that schoolchildren who consumed more fast food increased their risk of overweight or obesity (16). One survey also presents evidence that children who live near fast-food restaurants have higher risks of overweight and obesity than children who do not (17). It may be interesting for future studies to take into consideration the number of fast-food establishments that schoolchildren pass on their way to school. This consideration is suggested because of the discovery that walking and biking to school seems to be raising the risk for excess weight in schoolchildren who participated in our intervention. The popular opinion remains, however, that frequent walking and biking is a beneficial way of maintaining a healthy weight (18).

Improvements in physical activity behaviors were not as significant. The lack of safe places such as parks and sport fields where adolescents can be active may have prevented the intervention group from having an increase in getting the recommended level of physical activity. Some interventions did not see a significant increase in physical activity (19,20), while others did (21,22). One school-based intervention conducted in Belgium was able to significantly increase physical activity behaviors by providing game equipment to schoolchildren during recess and lunch breaks (22). The intervention had the advantage of a small group of 249 schoolchildren, and as a result they were able to supply the students with accelerometers and enough game equipment to increase physical activity behaviors (22). Because this intervention program was large, we could not use measuring devices, and distributing enough game equipment to satisfy the number of participants was impossible.

One review of numerous school-based physical activity interventions noted that interventions that used classroom teachers instead of researcher staff showed more significant positive results (23). Another study showed that interventions with family-based components were more effective than school-based components alone in increasing physical activity behaviors of schoolchildren (24). Establishing a healthy environment is critical to the prevention of risky lifestyle behaviors by adolescent schoolchildren (25). Parents play a large role in modeling healthy behaviors and in promoting an environment that encourages healthy eating and physical activity behaviors (26). The discovery, by our study and others, that excess weight in low-income and middle-income income countries is a problem primarily seen in adolescents from high socioeconomic backgrounds, further increases the importance of the role of parents (27). However, as children begin spending more time at school, the responsibility of schools to encourage healthy behaviors becomes even more important (11). School lunch programs and physical activity courses make it easier for numerous schools to regulate the nutritional and physical activity habits of adolescents (14). Creating a healthy environment for children requires many sectors of the community to participate in implementing societal, infrastructural, and policy change.