Is Obesity Protective in the Elderly?
Wednesday, November 23, 2011
Regular readers of these pages will by now be quite familiar with the ‘obesity paradox’ – the rather consistent finding that people with chronic disease (e.g. heart failure, chronic obstructive lung disease, end-stage kidney failure, etc.) tend to have lower mortality rates that skinny people with these conditions.
This raises the question whether or not obesity may generally be ‘protective’ in the elderly, who often have such conditions.
This question was now addressed by Jiska Cohen Mansfield and Rotem Perach from Tel Aviv University, in a paper just published in the Journal of Aging Research.
The authors looked at data from 1369 participants aged 75-94 from the Longitudinal Aging Study (CALAS), a national survey of a random sample of older Jewish persons in Israel conducted during 1989–1992.
Based on the mortality data at 20-year follow up, extracted from the Israeli National Population Registry, obesity was a significant predictor of higher mortality in persons aged 75 to 84 compared to ‘non-obese’ individuals.
Past the age of 85, however, obesity was no longer a predictor of mortality and, if anything, appeared to have a (non-significant) ‘protective’ effect.
In contrast, being underweight was consistently predictive of mortality.
These findings certainly support the notion that obesity (at least when measured by BMI) may be less of a health concern in the very elderly and may indeed signal better health than being skinny.
The authors provide several possible explanations for their findings:
“Lower rates of osteoporosis in heavier persons, possibly due to greater weight-bearing bone formation, may reduce their risk of falls and subsequent potential trauma. Obesity may also provide energy reserves in times of stress, illness, and trauma. In addition, obesity may prolong the period of predeath weight loss, as aging is associated with decreased food intake.”
Thus, as the authors discuss:
“..with the increasing numbers of old-old persons and of their life expectancy, extra attention is often given to avoiding obesity. Current findings suggest that such an emphasis may not apply to those advancing towards old-old age, at least as far as mortality is concerned.”
Sounds like it may be time to tell your Grandma to go off her diet?
AMS
Toronto, Ontario
p.s. Hat tip to Morgan Downey for alerting me to this article
Cohen-Mansfield J, & Perach R (2011). Is there a reversal in the effect of obesity on mortality in old age? Journal of aging research, 2011 PMID: 21966593
Wednesday, November 23, 2011
Maybe if you can get to old old age with obesity and lots of co-morbidities, you have a very robust constitution to begin with. e.g. it shows how good your body is, to be able to deal with so many problems at once, rather than the problems offering protection.
Thursday, November 24, 2011
Dear Arya, thanks for posting about the obesity paradox. It is very much likely that selection bias explains why obesity seems to protect from death in old age. Only the healthiest obese persons will survive to the old age and all the other obese persons have died earlier to obesity-related diseases etc. I think it is important to remember, when talking about older people, that there are also other meaningful outcomes than death. It is clearly shown that obesity in old age causes functional limitations and disability, which are very important in terms of quality of life in old age. Nevertheless, I wouldn’t either recommend weight loss to older obese persons, but healthier diet and physical exercise won’t do harm at any age.
Sunday, March 18, 2012
Even the authors of this study admit that it is flawed because it could use only BMI as a measure of obesity. An Olympic sprinter is obese by this measure.