PYY and anorexia nervosa: The detrimental impacts of PYY on osteogenesis, as observed in the majority of preclinical investigations, receive further validation from observational inquiries revealing a negative correlation between heightened fasting PYY levels and a BMD in physically active premenopausal women and those afflicted by anorexia nervosa (Scheid et al., 2011; Utz et al., 2008).