Future non-invasive studies that evaluate FGF21 in vivo can investigate changes in circulating parameters such as obesity-associated inflammatory cytokines to indirectly assess adipose tissue inflammation (59), or determine if there are preferential sites of lipolysis in the adipose tissue [e.g., with computed tomography (CT)] (60). The gene discussed is FGF21; the disease is obesity due to melanocortin 4 receptor deficiency.