Chrononutrition and Physical Fitness in Schoolgirls Aged 10–14 Years: Associations with Obesity Risk

Chrononutrition, which emphasizes the timing, frequency, and regularity of eating in alignment with circadian rhythms, has emerged as an important yet understudied determinant of obesity, particularly in children and adolescents. We aimed to compare chrononutrition and physical fitness between elementary and intermediate schoolgirls and to examine their associations with obesity. Methods: This cross-sectional study included 457 schoolgirls aged 10–14 years from elementary and intermediate schools. Chrononutrition behaviors were evaluated. Anthropometric measurements and physical fitness, including handgrip strength, standing long jump, and 20 m shuttle run, were assessed. Fasting blood glucose and lipid profile were determined using capillary blood samples. Results: Compared with intermediate students, elementary school students demonstrated more favorable meal-related behaviors, longer overnight fasting durations, and better dietary intake (p < 0.05), along with higher VO2 max and higher standing long jump performance. Conversely, intermediate students exhibited greater absolute handgrip strength. A higher number of meals/day (aOR = 0.68, p = 0.039) and a longer interval between the last meal and bedtime (aOR = 0.78, p = 0.013) were inversely associated with obesity. Furthermore, higher HGS/BMI was associated with lower odds of obesity (aOR = 0.01, p < 0.001), while HDL cholesterol was inversely associated with obesity (aOR = 0.91, p < 0.001). Conclusions: Chrononutrition behaviors and physical fitness varied across school stages and were associated with obesity among school-aged girls. Higher meal frequency, a longer interval between the last meal and bedtime, and greater handgrip strength relative to body mass index (HGS/BMI) were associated with lower odds of obesity. Non-obese students also demonstrated higher VO2 max. These findings suggest that chrononutrition behaviors and physical fitness may contribute to obesity prevention, underscoring the importance of early nutrition and physical activity interventions.