Is Obesity Protective in the Elderly?

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?

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