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Am J Clin Nutr. 2013 Nov;98(5):1298-308. doi: 10.3945/ajcn.113.064410. Epub 2013 Sep 4.

Belief beyond the evidence: using the proposed effect of breakfast on obesity to show 2 practices that distort scientific evidence.

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Office of Energetics (AWB and DBA), the Nutrition Obesity Research Center (AWB, MMBB, and DBA), the School of Public Health (AWB and DBA), and the Department of Nutrition Sciences (MMBB and DBA), University of Alabama at Birmingham, Birmingham, AL.



Various intentional and unintentional factors influence beliefs beyond what scientific evidence justifies. Two such factors are research lacking probative value (RLPV) and biased research reporting (BRR).


We investigated the prevalence of RLPV and BRR in research about the proposition that skipping breakfast causes weight gain, which is called the proposed effect of breakfast on obesity (PEBO) in this article.


Studies related to the PEBO were synthesized by using a cumulative meta-analysis. Abstracts from these studies were also rated for the improper use of causal language and biased interpretations. In separate analyses, articles that cited an observational study about the PEBO were rated for the inappropriate use of causal language, and articles that cited a randomized controlled trial (RCT) about the PEBO were rated for misleadingly citing the RCT.


The current body of scientific knowledge indicates that the PEBO is only presumed true. The observational literature on the PEBO has gratuitously established the association, but not the causal relation, between skipping breakfast and obesity (final cumulative meta-analysis P value <10(-42)), which is evidence of RLPV. Four examples of BRR are evident in the PEBO literature as follows: 1) biased interpretation of one's own results, 2) improper use of causal language in describing one's own results, 3) misleadingly citing others' results, and 4) improper use of causal language in citing others' work.


The belief in the PEBO exceeds the strength of scientific evidence. The scientific record is distorted by RLPV and BRR. RLPV is a suboptimal use of collective scientific resources.

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