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An Epidemic of Obesity Myths
BMI Report Cards

As of June 2005, legislators in 12 states have proposed putting students’ BMI on their report cards. Arkansas and Pennsylvania have already adopted such a measure. In addition to all the problems associated with the BMI, many studies have found that it is a particularly poor measure of body composition in children.

No Child with a fat behind

"…the validity of BMI as a measure of adiposity [excess fat] in children has not been established. There are well-known limitations regarding the use of BMI. For example, BMI is generally defined in adults as an index of adiposity that is largely independent of stature; however, this property of BMI in adults does not necessarily hold true in children … In addition, validity studies using BMI to identify children with excess adiposity have generally documented low to moderate sensitivities, which indicate only a poor to fair identification of those who are truly overweight, as determined from %BF … Health care professionals should, therefore, note that children and younger adolescents, particularly boys, who are tall for their ages may have large BMI values as a consequence of stature rather than excess adiposity."
Pediatrics, 2001

"…use of BMI during adolescence can lead to overestimation of the extent of increase in body fat, since the increase in BMI at younger ages includes increases in lean body mass."
Lancet, 2005

"In both infancy and childhood, a given BMI can embrace a wide range of percentage body fat … BMI is of limited use as a measure of body fatness in individuals in both infancy and childhood. The development of BMI with age may be disproportionately due to either FFM [fat free mass] and FM [fat mass] at different time points."
International Journal of Obesity, 2000

"However, the present study has demonstrated that the relationship between BMI and fatness in individuals is poor, both in infancy and childhood. Obesity is an excess of body fat, not an excess of body weight."
International Journal of Obesity, 2000

"The potential pitfalls of using BMI as an index of fatness in early life have been noted previously, but, paradoxically, much of our understanding of the development of fatness is based only on such proxy measures … The actual relationship between early fatness and later obesity is unknown, and will remain so until whole-body fatness is measured at each time point."
International Journal of Obesity, 2000