More on Body Fat Cutoff Points

Abstract

To the Editor: We read with interest the recent article by Oreopoulos et al1 that reported the association between body composition and chronic heart failure. In the article, the authors state that “…WHO [World Health Organization] has also proposed a definition of obesity as greater than 25% body fat in men and greater than 35% body fat in women,” with the 1995 WHO Technical Report2 serving as the reference for this statement. As a matter of fact, the mentioned WHO Technical Report makes no recommendation regarding the criteria of percentage of body fat (PBF) for the diagnosis of obesity. However, the WHO Technical Report refers to a Swedish study in which the average PBF (by underwater weighing) was 25% in men and 30% in women aged 45 to 49 years: Using underwater weighing of 200 healthy Swedish men and women aged 45-78 years, Bjontorp & Evans[3] reported changes in the percentage of weight that is represented by body fat. At 45-49 years, men averaged 25% fat; this seemed to stabilize at 38% at age 60-65 years. Women had more body fat than men at 45-49 years (30%) and stabilized at an average of 43% at 55-59 years. Between 60 and 78, neither men nor women showed much change in percentage body fat.2, p378 Thus, the WHO report did not set any threshold of PBF for defining obesity. Despite that fact, several authors have continued to misquote the PBF threshold. The misquotation appears to have begun in an article published in 1998,4 which stated that “Obesity is characterised by an increased amount of body fat, defined in young adults as body fat >25% in males and >35% in females, corresponding to a body mass index (BMI) of 30 kg/m2 in young Caucasians” and attributed these thresholds to the WHO Technical Report.2 Moreover, subsequent studies5-10 continued referring to that article4 and/or the 1995 WHO Report2 as the primary source for the PBF thresholds. In 2004, a WHO Expert Committee stated without reference that “…overweight (≥25 kg/m2) corresponded to 31-39% (mean 35%) body fat in females and 18-27% (mean 22%) body fat in males. If these criteria for the percentage body fat for overweight and obesity are applied to the Asian populations, the corresponding BMIs can be calculated with country-specific equations.”11 These are quoted as “facts” without a sound scientific basis because no original scientific validation has been published. In summary, an initial misrepresentation of a WHO Technical Report has led to a trail of subsequent misquotations. To date, there is no validated threshold of body fatness for defining obesity.