aMetabolism Unit, Division of Endocrinology, Massachusetts General Hospital and Harvard Medical School

bMassachusetts General Hospital Weight Center, Department of Medicine, Division of Endocrinology, Metabolism Unit, Boston, Massachusetts, USA

Correspondence to Mabel Toribio, MD, Metabolism Unit, Division of Endocrinology, Massachusetts General Hospital, 55 Fruit Street, 5 LON 207, Boston, MA 02114, USA. ORiCD ID: 0000-0002-4153-5568. Tel: +1 617 724 2826; fax: +1 617 724 8998; e-mail: [email protected]