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Just as smart but not as successful: obese students obtain lower school grades but equivalent test scores to nonobese students



The obesity epidemic in industrialized nations has important implications for education, as research demonstrates lower academic achievement among obese students. The current paper compares the test scores and school grades of obese, overweight and normal-weight students in secondary and further education, controlling for demographic variables, personality, ability and well-being confounds.


This study included 383 eighth-grade students (49% female; study 1) and 1036 students from 24 community colleges and universities (64% female, study 2), both drawn from five regions across the United States.


In study 1, body mass index (BMI) was calculated using self-reports and parent reports of weight and height. In study 2, BMI was calculated from self-reported weight and height only. Both samples completed age-appropriate assessments of mathematics, vocabulary and the personality trait conscientiousness. Eighth-grade students additionally completed a measure of life satisfaction, with both self-reports and parent reports of their grades from the previous semester also obtained. Higher education students additionally completed measures of positive and negative affect, and self-reported their grades and college entrance scores.


Obese students receive significantly lower grades in middle school (d=0.83), community college (d=0.34) and university (d=0.36), but show no statistically significant differences in intelligence or achievement test scores. Even after controlling for demographic variables, intelligence, personality and well-being, obese students obtain significantly lower grades than normal-weight students in the eighth grade (d=0.39), community college (d=0.42) and university (d=0.31).


Lower grades may reflect peer and teacher prejudice against overweight and obese students rather than lack of ability among these students.

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We thank Brent Bridgeman and Cathy Wendler for insightful comments on a previous version of this manuscript.


All statements expressed in this article are of the authors and do not reflect the official opinions or policies of the University of Sydney or the Educational Testing Service.

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Correspondence to C MacCann.

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MacCann, C., Roberts, R. Just as smart but not as successful: obese students obtain lower school grades but equivalent test scores to nonobese students. Int J Obes 37, 40–46 (2013).

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  • academic achievement
  • conscientiousness
  • well-being
  • prejudice

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