Comments about body mass index and body fat in older women
This journal article thinks that a BMI of 25.5 is a better obesity threshold. It defines "true obesity" as having a body fat percentage over 35%. That’s a common definition, but it is arbitrary nevertheless.
The article showed a graph of the BMI and body fat percentages of the older women in the study. Notice that the great majority of these women have a body fat percentage over 35%.
Is it natural and normal, or is it problem and unhealthy that the majority of older women have a body fat percentage over 35%? No-one knows for sure.
For younger and middle-aged adults, a body fat percentage over 35% is definitely associated with higher risks of disease, but studies of older adults hasn’t been able to prove a significant extra risk.
In fact, older adults have a higher mortality rate2 if they have a lower body mass index.
A different study1, of adult women of all ages, showed that a BMI of 25.85 is the least-risky in terms of diseases related to being overweight or underweight.
So maybe it’s not such a good idea after all, to label the majority of older woman as obese, if their BMI is over 25.5, when might actually be reasonably healthy after all.
- Allison D, Faith M, Heo M. Townsend-Butterworth D, Williamsom D. Meta-analysis of the effect of excluding early deaths on the estimated relationship between body mass index and mortality. Obes Res 1999; 7: 342-54.
- Allison DB, Zhu SK, Plankey M, FaithMS, Heo M. Differential associations of body mass index and adiposity with all-cause mortality among men in the first and second National Health and Nutrition Examination Surveys (NHANES I and NHANES II) follow-up studies. Int J Obes Relat Metab Disord, Mar 2002;26(3):410-6
Update 2014. See this post about body mass index in the elderly for longest survival.