## Background ## Research into energy balance and growth has infrequently considered genetic sex, yet there is sexual dimorphism for growth across the animal kingdom. We test the hypothesis that sexual dimorphism for growth and body weight in birds is potentially dependent on hypothalamic agouti-related peptide (AGRP) expression, since previous research indicates hypothalamic AGRP expression is correlated with growth potential. ## Conclusion ## Expression of orexigenic peptides in the avian hypothalamus are correlated with sex differences in growth and body weight. The differences in gene expression between sexes provides further evidence of AGRP expression being correlated to growth potential. Results also suggest that gut-fill alone does not reduce orexigenic gene expression.