Introduction: Despite its widespread use, the body mass index (BMI) still has limitations for assessing adiposity in pediatric populations, particularly due to its inability to differentiate between fat mass and muscle mass. Objective: To examine the association between BMI, triponderal mass index (TMI), and body fat percentage (%BF) in a representative sample of children and adolescents. Methodology: This cross-sectional study included 824 students (females n=370, males n=454) from public schools in Quintero, Chile. Participants were stratified by age: children aged 6-9 years (n=355) and adolescents aged 10-19 years (n=469). Weight and height were measured to calculate BMI-z scores, TMI (weight/height³), and %BF (Slaughter formula). Data are presented as mean and standard deviation. Pearson's correlation coefficient (r) assessed associations, while the coefficient of determination (R²) quantified effect sizes. Results: High prevalence of overweight was observed: 51.5% in children (6-9 years) and 59.8% in adolescents (10-19 years). Significant correlations (p<0.01) were found between indices and %BF: in children, BMI showed r=0.792 with %BF and TMI showed r=0.728; in adolescents, correlations were r=0.728 for BMI and r=0.739 for TMI. TMI demonstrated greater explanatory power (R²) for %BF in girls (R²=0.571) and male adolescents (R²=0.534), while BMI was a better predictor in boys (R²=0.747) and female adolescents (R²=0.623). Conclusions: TMI showed stronger association with %BF in girls and male adolescents, while BMI was more accurate in boys and female adolescents. These findings highlight the need to establish standardized cut-off points for TMI in pediatric populations.

Background: This study aimed to determine the proportion of Ecuadorian preschool children meeting the World Health Organization (WHO) 24‐hour movement behaviour guidelines for physical activity, sedentary behaviour and sleep, to examine differences by sex and geographic location and to evaluate the feasibility and acceptability of the International Study of Movement Behaviours in the Early Years (SUNRISE) protocol. Methods: In this pilot study, a total of 108 children aged 3–4 years from kindergartens in Quito (Ecuador) participated in 2024. Physical activity, sleep and sedentary behaviour were evaluated using accelerometry ( ActiGraph wGT3x‐BT ). Gross and fine motor skills were evaluated using validated tasks, and executive functions were assessed via the Early Years Toolbox. Results: Only 11.8% of children met all three WHO recommendations of 24‐hour movement behaviours, while 16.1% did not meet any. Boys showed higher compliance with the physical activity guidelines compared to girls, and urban children demonstrated slightly better adherence to the screen time guideline. A total of 100% of participants completed anthropometric, executive function and motor skill assessments, respectively. Additionally, 86.1% of children provided at least one valid day of accelerometer data, and 75.9% accumulated three or more valid days, supporting the feasibility and acceptability of the SUNRISE study protocol in this population. Conclusion: This pilot study demonstrated the feasibility and acceptability of the SUNRISE study methods among Ecuadorian children. Given the low proportion of children meeting the WHO movement guidelines, long‐term strategies are needed to promote healthier lifestyles from early childhood in Ecuador.

Body dissatisfaction is prevalent among adolescents and linked to adverse outcomes. This study examined sociodemographic and anthropometric factors associated with body dissatisfaction in Spanish adolescents. Cross-sectional data from the Eating Healthy and Daily Life Activities (EHDLA) study (N = 1378 students aged 12–17 years) were analyzed. Body dissatisfaction was assessed using the Body Image Dimensional Assessment (BIDA) instrument (overall index and three subscales). Variables included age, sex, socioeconomic status, immigrant status, family structure, parental education, area of residence, and body mass index. Robust multivariable linear models adjusted for all a priori covariates were fitted. Multivariable complete-case models included n = 747 of 1378 adolescents. Younger age, female sex, and excess weight were associated with higher body dissatisfaction on one or more BIDA dimensions. Excess weight showed the largest standardized associations and was linked to all BIDA dimensions (p < 0.001). Maternal educational attainment was not significant in the fully adjusted primary models but remained associated with lower Body Dissatisfaction Score in a reduced-model sensitivity analysis. No significant associations were observed for socioeconomic status, immigrant status, family structure, or area of residence in the primary models. Younger adolescents, female adolescents, and those with excess weight represent subgroups at greater risk of body dissatisfaction. These findings underscore the need for targeted prevention and intervention strategies addressing both anthropometric and sociodemographic risk factors during adolescence.

Background: Men display higher absolute fat oxidation rates during exercise than women, but whether fat-free mass (FFM) moderates the substrate–intensity relationship in a sex-specific manner remains untested. Methods: In this cross-sectional laboratory study, we evaluated 37 competitive athletes (20 women, 17 men; age 22 ± 5 years) using dual-energy X-ray absorptiometry (DXA) and indirect calorimetry during incremental treadmill exercise (538 min-by-min observations) to evaluate a sex × FFM × intensity interaction using linear mixed-effects models. Results: The primary sex × FFM × intensity interaction was non-significant ($\beta =+0.014$, 95 % CI −0.021 to +0.049; $p=0.443$). Absolute maximal fat oxidation (MFO) was higher in men ($0.826\pm 0.234$ vs. $0.655\pm 0.175\mathrm{g}\cdot {\min }^{-1}$; $p=0.038$), but it disappeared when normalised to FFM ($15.45\pm 4.19$ vs. $15.74\pm 4.85\mathrm{mg}\cdot {\mathrm{kg}\mathrm{FFM}}^{-1}\cdot {\min }^{-1}$; $p=0.847$). Interestingly, a strong sex × adiposity (DXA body-fat percentage, %) interaction was identified ($\beta =-0.440$, $q<0.001$), with higher adiposity linked to higher fat oxidation in men ($\beta =+0.339$, $p<0.001$) but lower in women ($\beta =-0.115$, $p=0.010$). Conclusions: Adiposity was identified as the most significant sex-specific moderator, with evidence showing that it is associated with greater fat oxidation in men and lower fat oxidation in women. The male advantage in absolute fat oxidation reflected greater FFM, because MFO per kilogram of FFM did not differ between sexes; muscle oxidative capacity was not measured directly. However, the exploratory nature of the study requires confirmation in future research.

Background: Screen-based distractions during meals are increasingly common during adolescence and have been linked to less healthy eating behaviors. Chronotype, an individual’s circadian preference for morningness or eveningness, is associated with differences in alertness, self-regulation, and recreational screen use across the day, which may in turn influence susceptibility to distractions during meals. However, the relationship between chronotype and eating distraction behaviors remains largely unexplored. Therefore, this study examined the association between chronotype and eating distraction behaviors in Spanish adolescents. Methods: A cross-sectional study was carried out in 820 adolescents aged 12–17 years from the Eating Healthy and Daily Life Activities (EHDLA) project. Chronotype was assessed using the Morningness–Eveningness Scale for Children and classified as evening, intermediate, or morning type. Eating distractions were evaluated using a composite score that included eating lunch or dinner while watching television, using mobile devices or social networks during meals, and eating while standing. Associations were examined using ordinal regression models (proportional odds), with eveningness as the reference category; both unadjusted and adjusted models are reported, with adjustment for relevant sociodemographic and lifestyle covariates. Results: In adjusted ordinal regression models with eveningness as reference, morningness was related to lower odds of being in a higher eating distractions category (odds ratio [OR] = 0.53; 95% confidence interval [CI] 0.35–0.82; p = 0.004). Morningness was also associated with lower odds of a higher category of television viewing during meals (OR = 0.59; 95% CI 0.38–0.93; p = 0.024). No significant associations were identified for eating while using a phone or social networks or for eating while standing. Conclusions: Chronotype was independently associated with eating distraction behaviors in Spanish adolescents, with evening types showing a less favorable pattern. These findings suggest that circadian preference may be relevant when addressing mealtime behaviors during adolescence and could help inform future health promotion strategies.