Sex Differences in Leptin Levels in Children and Adolescents with Normal Weight and Overweight/Obesity Across...

Leptin levels differ significantly between adult men and women, it is unknown whether these sex differences arise during puberty in children with normal weight (NW) or overweight (OW)/obesity (OB).

To analyze sex differences in leptin levels and body mass index SD score across pubertal stages in children with NW and OW/OB.

Eligible studies were obtained from Medline, Embase, Web of Science, Cochrane, and CINAHL from inception until February 2025.

Twenty-four of 1713 studies assessing leptin levels in children aged 5 to 19 years were included.

Two reviewers independently extracted data and assessed study quality.

We performed subgroup meta-analysis stratified for pubertal stage using random effects model to estimate the weighted mean difference in R. Girls with NW had higher leptin levels than boys at all pubertal stages (pooled mean difference [MD]: 3.99; 95% CI, 2.63-5.35). In children with OW/OB, no significant differences were found in the 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, body mass index SD score was higher in boys than girls (MD: -0.67; 95% CI, -0.74 to -0.61).

The sex-specific differences in leptin levels, characteristic of normal-weight (pre-)pubertal children is lost in obesity. Therefore, leptin levels alone are unlikely to explain why obesity accelerates puberty in girls more than in boys. A combined effect with other factors, such as sex dimorphism in kisspeptin, may play a role.