Fto immunoreactivity is widespread in the rodent brain and abundant in feeding-related sites, but the number of Fto-positive cells is not affected by changes in energy balance.

A single nucleotide polymorphism in the FTO gene is associated with obesity in humans. Evidence gathered in animals mainly relates energy homeostasis to the central FTO mRNA levels, but our knowledge of the Fto protein distribution and regulation is limited. Fto, a demethylase and transcriptional coactivator, is thought to regulate expression of other genes.