Methodological Challenges in Studies Examining the Effects of Breakfast on Cognitive Performance and Appetite in Children and Adolescents

methodological review, no pooled sample

Children and adolescents in breakfast-cognition studies generally.

Narrative methodological critique by the same group that produced the two major breakfast systematic reviews - i.e. the people best placed to say why their own literature does not support the claim popularly attributed to it. Graded D as expert opinion/narrative review; it is cited here for the design critique, not for any effect estimate.

The belief that breakfast is "the most important meal of the day" has been challenged by new evidence. Substantiating any positive breakfast effect on cognition is hampered by, among other things, the choice of objective cognitive tests (bespoke lab batteries rather than independent standardized measures), study location and design (artificial lab settings rather than classrooms), sampling, fixed vs ad libitum breakfast provision, the definition and self-report measurement of HABITUAL breakfast consumption, non-blindable treatment conditions, the difficulty of isolating the direct effect of breakfast from everything correlated with eating it, the conflation of acute and chronic effects, and confounding variables. This is the definitive statement of why the breakfast-cognition literature systematically overstates itself.

The paper explicitly names confounding of habitual breakfast consumption as a core methodological problem, though it does not frame it in genetic terms. Habitual breakfast eating is a household-routine variable, and household routine is a proxy for heritable parental traits.