TSHR activation stimulates early differentiation (favoring BAT formation?) but renders preadipocytes refractory to PPARgamma-induced adipogenesis. In neither case did lipid-containing vacuoles accumulate, suggesting that terminal stages of differentiation were inhibited.

A decrease in fasting FGF19 is associated with the development of NAFLD in obese adolescents. A decrease in fasting FGF19 levels may be a new important risk factor for NAFLD and the metabolic syndrome in adolescents. Further studies are needed to explain whether exogenous delivery of FGF19 might be therapeutically beneficial.

FGF23 seems to be a novel factor contributing to insulin sensitivity. Further investigations are needed to define its role in the development of MS.

In adolescents with simple obesity and insulin resistance, FGF23 levels are lower compared with obese adolescents with normal HOMA-IR.