[extropy-chat] Overweight people live longer

[Brian M. Delaney]

Reason skrev:
 > I should point out that there are any number of
 > good studies demonstrating exactly the opposite.
 > One can't draw conclusions based on any one
 > study in this field.


Agreed.

But far more importantly, no conclusions about the benefits of a CR 
program can be drawn from studies showing a correlation between weight 
and mortality. People trying to draw such a conclusion are committing a 
serious logical error, one with potentially devastating health 
consequences for those who buy the error.

"CR leads to a reduction in weight." Yes.

"A reduction in weight is a sign of CR." No.

CR is not about being thin. Naturally obese mice (ob/ob) on severe CR 
are still chubby, but live much longer than naturally thin mice not on 
CR. Energy-restriction shifts resources away from growth and 
reproduction towards repair and maintenance. Doesn't matter what you weigh.


Indeed, the assumption (or false conclusion) that 
"accidental/unintentional CR" is more likely to be found among the 
underweight is not only wrong, it may even be backwards. People in the 
countries whre these mortality studies tend to be conducted who are 
naturally thin have LESS reason to restrict their food intake (and note: 
food restriction is not the same as Calorie restriction -- though that's 
a minor point), given societal pressures to be thin.

The way to determine whether or not CR reduces mortality is to look at 
people on CR and compare them to people not on CR. This is being done. 
Some initial results include those reported by Fontana [1].

It will take a long time before we can be certain that CR dramatically 
reduces mortality, but it seems extraordinarily like that it does so, 
and we can be certain that risks of diseases of aging (certainly, type 2 
diabetes) is reduced significantly.

There are LOTS of sensible reasons not to be on CR. Believing that "it 
doesn't work" isn't one of them.

Best,
Brian


[1] Fontana L, Meyer TE, Klein S, Holloszy JO.
"Long-term calorie restriction is highly effective in reducing the risk 
for atherosclerosis in humans."
Proc Natl Acad Sci U S A. 2004 Apr 27;101(17):6659-63. Epub 2004 Apr 19.

-- 
Brian M. Delaney
President, The Calorie Restriction Society
http://www.calorierestriction.org