Trunk Fat Negatively Influences Skeletal and Testicular Functions in Obese Men : Clinical Implications for the Aging Male

Abstract EN

Osteocalcin (OSCA) seems to act as a negative regulator of energy metabolism and insulin sensitivity.

Evidence from male rodents suggests that OSCA may also regulate testosterone (T) synthesis.

Using a cross-sectional design, we evaluated OSCA, 25(OH) vitamin D, T, 17β-estradiol (E2), homeostasis model assessment of insulin resistance (HOMA-IR), and body composition in 86 obese (mean BMI = 34) male subjects (18–69 yr old).

Independently from BMI, an inverse relationship between trunk fat percentage and plasma T (r2=−0.26, P<0.01) and between HOMA-IR and OSCA levels (r2=−0.22, P<0.005) was found.

OSCA levels, as well as vitamin D, decreased significantly for higher BMI with significant differences above 35 (P<0.01).

A direct correlation between T and bone mineral density at lumbar (BMDL) and neck (BMDH) (P<0.001, r2=−0.20; P<0.001, r2=−0.24) was found, independently from age.

An inverse correlation between E2 levels, BMDL, and BMDH (P<0.001, r2=−0.20; P<0.001, r2=−0.19) was observed.

These data provide new evidences that a relationship between trunk fat mass, insulin sensitivity, OSCA and T synthesis occurs.

This new relationship with skeletal health has relevant implications for the aging male, suggesting OSCA as a novel marker of metabolic and gonadal health status.