In 2009, important health organizations met to construct a Joint Scientific Statement (JSS) intended to harmonize the diagnosis of metabolic syndrome worldwide. The JSS aimed to unify the diagnostic criteria of metabolic syndrome, particularly in relation to whether to include abdominal obesity as a criterion of diagnosis. A large part of the JSS is devoted to discussing the diagnosis of abdominal obesity. More specifically, 9 of the 16 papers focused on abdominal obesity. Continuing this emphasis, we discuss the harmonization of the diagnosis of metabolic syndrome worldwide, specifically focusing on the need to improve the diagnosis of abdominal obesity.