Objective:

To analyze sex differences in leptin levels and body mass index SD score across pubertal stages in children with normal weight (NW) and overweight/obesity (OW/OB), highlighting the importance of understanding these differences for public health.

Key Findings:

• Girls with NW had higher leptin levels than boys at all pubertal stages (MD: 3.99; 95% CI, 2.63-5.35), based on a comprehensive review of the included studies.
• In children with OW/OB, no significant differences in leptin levels were found in prepubertal and pubertal stages.
• At the postpubertal stage, leptin levels were higher in girls compared to boys (MD: 14.60; 95% CI, 0.95-28.25), based on 1 included study.
• In pubertal children with OW/OB, BMI SD score was higher in boys than girls (MD: -0.67; 95% CI, -0.74 to -0.61), indicating a need for further investigation.

Interpretation:

Sex-specific differences in leptin levels characteristic of normal-weight prepubertal children are lost in obesity, suggesting that leptin levels alone do not explain the accelerated puberty in girls compared to boys, warranting further research into other contributing factors.

Limitations:

• Limited number of studies included in the analysis, which may affect the generalizability of the findings.
• Potential variability in study quality and methodologies, such as differences in sample sizes and measurement techniques.

Conclusion:

Leptin levels may not solely account for the differences in pubertal timing between sexes, indicating a need for further research into other contributing factors.