Monday, October 29, 2007

Weight benefit in old age

old man
Beyond eighty years of age the so-called ideal weight may be bad for your health; the so-called obese turn out to live longest.

Regular readers of this blog will not be surprised because a number of studies have shown health benefits of a higher body weight in old age, for instance in elderly asthmatics, and two more studies are listed here.

Yet another study of this kind has just been published with this finding about body mass index and mortality in elderly persons: the higher the body mass index, the lower the mortality. More than four hundred elderly persons, about half of them women, have been admitted to an acute geriatric ward in Israel. The body mass index at admission day has been calculated, and their fate after the release has been followed-up four years on average. About half of them died during this time, and those who died had a lower body mass index (24.1) than those who survived (26.3). According to the WHO definition, death has been linked to "normal weight" and survival to "overweight". The fattest persons, with a body mass index higher than 28 (so-called "obese") had the lowest mortality, only 9.6 percent of them died per year. The thinnest persons, with a body mass index below 22 (generally labelled as "ideal weight") had the highest mortality, 24 percent of them died per year.

The question of sickness

Of course, findings gained in certain groups may not be generalized to all persons. For instance, the people of this Israeli study have been admitted to a hospital, so they have been sick, and the findings may not apply to healthy people. But it is important to note that they have been admitted due to acute conditions, such as accidents or infections, and not for a chronic illness which may have caused weight loss.

The researchers also applied a statistical filter to remove the direct influence of known risk factors such as male sex (men die earlier than women), age (life expectancy diminishes with age), renal failure and diabetes. Even after these filters, a higher weight turned out to remain beneficial in these elderly persons.

Take-aways: In persons beyond eighty years of age, a higher weight is linked to a longer life, but it remains to be shown to what extent this may be a benefit of body fat (as a vitality reserve) or rather the influence of serious diseases causing weight loss.

I'll be keeping tabs on the research...

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