Interesting paper on how it's probable that a large number of "normal weight" post-menopausal women are obese by body fat level:
Measuring Adiposity in Patients: The Utility of Body Mass Index (BMI), Percent Body Fat, and Leptin
Nirav R. Shah , Eric R. Braverman 2012
While there was agreement for 60% of the sample, 39% were misclassified as non-obese based on BMI, while meeting obesity criteria based on percent body fat. Only 1% was classified as obese based on BMI, but non-obese by percent body fat. A total of 48% of women were misclassified as non-obese by BMI, but were found to be obese by percent body fat. In sharp contrast, 25% of men were misclassified as obese by BMI, but were in fact non-obese by percent body fat (i.e. the muscular body morphology)...
BMI significantly underestimates prevalence of obesity when compared to DXA direct measurement of percent body fat...
This misclassification was seen more commonly in women than in men and occurred more frequently with advancing age in women. A more appropriate cut-point for obesity with BMI is 24 for females and 28 for males (see Table 4). These new cut-points increased diagnostic sensitivity with small losses in specificity. Clinicians should consider using 24 as the BMI cut-point for obesity in women, in order to maximize diagnosis and prevention of obesity-related co-morbidities. Public health policymakers should also consider these more accurate cut-points in designing interventions. The Healthy People 2010 goal was to reduce rates of obesity (defined using BMI>30) from 23% in 1988–1994 to the target of 15%. Not only was this goal unmet, but in light of this data we may be much further behind than we thought. Our results document the scope of the problem of false-negative BMIs, emphasize the greater misclassification in women of advancing age, and confirm the improved precision available by gender specific revised cutoffs.
An individual's body composition might be a good index to metabolic health and how healthily someone ages. There are good advances in making diabetes and various other chronic illnesses manageable but for many of us, if it's possible that managing body composition prevents those illnesses, that might be a useful way to prolong our health in later life.