Table 1

Descriptive statistics of participants in the sample

Total (n=568)Normal leptin levels (n=485)Hyperleptinaemia (n=83)p Value*
 Mean or number(SD) or percentageMean or number(SD) or percentageMean or number(SD) or percentage
Chronological age
 Age (years)16.8†(0.3)16.8†(0.3)16.8†(0.3)NS
Serum leptin
 Males (μg/L)6.0†(9.6)2.2†(1.9)21.40†(13.1)<0.0001
 Females (μg/L)19.4†(14.4)16.0†(9.7)51.32†(12.7)<0.0001
 Height at 16 years (WHO z-score)−0.45†0.8−0.47†0.8−0.35†0.8NS
 Height at 16 years (CDC percentile)35.0†24.734.5†24.737.8†24.2NS
 BMI at 16 years (WHO z-score)0.63†(1.2)0.47†(1.1)1.58†(1.3)<0.0001
 BMI at 16 years (CDC percentile)64.4†28.061.4†27.481.4†25.3<0.0001
Weight status
 Normal weight35261.932967.82327.7<0.0001
Insulin sensitivity
PA patterns
 Weekly scheduled PA≤90 min32256.727556.74756.6NS‡
Diet habits
 Unhealthy diet16228.513728.32530.1NS‡
Parental education
 Mother's schooling: incomplete secondary37734.016834.62530.1NS‡
 Father's schooling: incomplete secondary15928.014028.91922.9NS‡
Type of secondary education
 Adult school9817.37916.31922.9NS‡
Iron supplementation (infancy)
 Non-added Fe23841.920542.33339.8NS‡
  • Normal weight: BMI z-score ≤1 SD; overweight: BMI z-score >1 and ≤2 SD; obesity: BMI z-score >2 SD.

  • Hyperleptinaemia defined according to the cut-offs published by Köster-Weber et al.

  • *Student's t-test, except as indicated.

  • †Values expressed as mean and (SD). Otherwise, values are number of observations and percentage.

  • ‡χ2 test (Pearson).

  • BMI, body mass index; CDC, Centers for Disease Control and Prevention; HOMA, homeostasis model assessment of IR; IR, insulin resistance; NS, not significant; PA, physical activity.