  Purpose: Factor analysis (FA) has become part and parcel in metabolic
syndrome (MBS) research. Both exploration- and confirmation-driven factor
analyzes are rampant. However, factor analytic results on MBS differ widely. A
situation that is at least in part attributable to misapplication of FA. Here,
our purpose is (i) to review factor analytic efforts in the study of MBS with
emphasis on misusage of the FA model and (ii) to propose an alternative factor
analytic strategy.
  Methods: The proposed factor analytic strategy consists of four steps and
confronts weaknesses in application of the FA model. At its heart lies the
explicit separation of dimensionality and pattern selection as well as the
direct evaluation of competing inequality-constrained loading patterns. A
high-profile MBS data set with anthropometric measurements on overweight
children and adolescents is reanalyzed using this strategy.
  Results: The reanalysis implied a more parsimonious constellation of
pathophysiological domains underlying phenotypic expressions of MBS than the
original analysis (and many other analyzes). The results emphasize correlated
factors of impaired glucose metabolism and impaired lipid metabolism.
  Conclusions: Pathophysiological domains underlying phenotypic expressions of
MBS included in the analysis are driven by multiple interrelated metabolic
impairments. These findings indirectly point to the possible existence of a
multifactorial aetiology.
