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Use of Body Fatness Cutoff Points

      To the Editor: In the July 2010 editorial of Mayo Clinic Proceedings, although correctly making the argument that “BMI [body mass index; calculated as weight in kilograms divided by height in meters squared] does not reflect true body fatness,” Lavie et al
      • Lavie CJ
      • Milani RV
      • Ventura HO
      • Romero-Corral A
      Body composition and heart failure prevalence and prognosis: getting to the fat of the matter in the “obesity paradox.”.
      refer to the “National Institutes of Health [NIH] criterion standards” for percent body fat (BF) as greater than 25% in men and greater than 35% in women. The reference provided for this statement is a pamphlet
      • US Department of Health and Human Services
      • National Institutes of Health
      WIN Weight Control Network. Understanding Adult Obesity. NIH Publication No. 06-3680.
      for the general public, issued by the Weight Information Network (WIN), an NIH initiative to provide “science-based information on weight control, obesity, physical activity, and related nutritional issues.” Although I did not find any mention of body fat (BF) cutoff points in that publication, an earlier version
      • US Department of Health and Human Services
      • National Institutes of Health
      WIN Weight Control Network. Understanding Adult Obesity. NIH Publication No. 01-3680.
      did state that “Most health care providers agree that men with more than 25 percent body fat and women with more than 30 percent body fat are considered obese.” Note the discrepancy in cutoff for women between the editorial and the pamphlet.
      The discrepancy in cutoff for women aside, assuming that the earlier version is the intended citation, it is a bit of a stretch to elevate an unreferenced statement from a WIN pamphlet to an “NIH criterion standard.” Moreover, as one of the authors of the editorial recently stated, “Unfortunately, neither the World Health Organization nor any major scientific society involved in the study of obesity has defined a normal value for BF%.”
      • Romero-Corral A
      • Somers VK
      • Sierra-Johnson J
      • et al.
      Normal weight obesity: a risk factor for cardiometabolic dysregulation and cardiovascular mortality.
      Regarding BMI, the World Health Organization and NIH cutoff point of 25 was chosen because, in most epidemiological studies, mortality in both men and women begins to increase above this value,
      • National Institutes of Health
      • National Heart, Lung, and Blood Institute
      Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: the evidence report. NIH Publication No. 98-4083.
      ie, there is evidence of a threshold effect. By contrast, there is little if any evidence to support that cutoff points of 25% in men and 35% (or 30%) in women are the optimal values for BF-based risk stratification. In the absence of a substantial body of literature characterizing the sex-specific relation between a continuum of BF percent values and morbidity and mortality, as well as potential moderating effects of age and race, the choice of BF percent cutoff points in research or clinical practice remains a highly subjective decision.

      REFERENCES

        • Lavie CJ
        • Milani RV
        • Ventura HO
        • Romero-Corral A
        Body composition and heart failure prevalence and prognosis: getting to the fat of the matter in the “obesity paradox.”.
        Mayo Clin Proc. 2010; 85: 605-608
        • US Department of Health and Human Services
        • National Institutes of Health
        WIN Weight Control Network. Understanding Adult Obesity. NIH Publication No. 06-3680.
        (Accessed September 29, 2010.)
        • US Department of Health and Human Services
        • National Institutes of Health
        WIN Weight Control Network. Understanding Adult Obesity. NIH Publication No. 01-3680.
        (Accessed October 14, 2001.)
        • Romero-Corral A
        • Somers VK
        • Sierra-Johnson J
        • et al.
        Normal weight obesity: a risk factor for cardiometabolic dysregulation and cardiovascular mortality.
        Eur Heart J. 2010; 31: 737-746
        • National Institutes of Health
        • National Heart, Lung, and Blood Institute
        Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: the evidence report. NIH Publication No. 98-4083.
        (Accessed Setpember 29, 2010.)

      Linked Article

      • Use of Body Fatness Cutoff Points–Reply–I
        Mayo Clinic ProceedingsVol. 85Issue 11
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          We appreciate Dr Snitker's interest in our recent editorial1 and his insightful comments regarding body fat (BF) and obesity. Additionally, we are aware of his clinical and research efforts in the area of obesity in children at the University of Maryland School of Medicine. Dr Snitker is correct that currently there is no definitive cutoff for percent BF in defining overweightness or obesity in men or women. In our efforts to simplify the message for readers, we referenced an easily accessible National Institutes of Health (NIH) publication2 that we thought was representative.
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