= 27d567bc2d48d9f40e9ccc20ea370b15)
Manfred comments on Evidence against Calorie Restriction - Less Wrong
You are viewing a comment permalink. View the original post to see all comments and the full post content.
= 783df68a0f980790206b9ea87794c5b6)
Loading…= b715d02e85f7b3b4ae65ca3d3e450868)
Subscribe to RSS Feed
Powered by Reddit
= f037147d6e6c911a85753b9abdedda8d)
You are viewing a comment permalink. View the original post to see all comments and the full post content.
Comments (23)
Also, skinny people die more than people near the border between normal and "overweight," for reasons not fully understood, though which may be at least partially due to tobacco use.
Being sick often makes you skinny. There are many causes of muscle wasting disorders, including many kinds of malnutrition.
Data collection on deaths began 5 years after collecting the BMI to try to limit this sort of effect, as they state in the summary. And they do a cause of death breakdown which eliminates the idea of a muscle-wasting disease.
60% of the excess mortality at low BMIs in the study was down to respiratory disease, most of which is due to smoking. Being skinny is a marker for being sick and for being old - both of which tend to come on before death, but neither of which are necessarily confined to the last 5 years of life. This kind of statistical association between being skinny and being ill is thought to explain most of the effect of increased mortility at low BMIs.
The question calorie restriction practitioners want the answer to is: "what is the effect of low BMI caused by low intake of dietary enegry while ensuring good nutrition on lifespan?" There is data on this question, but it mostly doesn't come from studies like this one - where the signal is dominated by people who are skinny because they are sick, old, malnourished or had developmental issues.
A good number of the experts who have considered this issue seem to think positive efefcts on health and lifespan in initially healthy western humans on sensible energy-restricted diets are likely to go down at least to to BMIs around 18. Some take their own weights down below that - but mostly confess that they are exploring rather poorly-charted territory.
I've been going with the hypothesis that people with a little more fat that what's considered healthy have more reserves for illness, operations, and/or cancer treatments.
I believe tobacco use has been considered in at least some of those studies.
So far as CR is concerned, a lot of thin people (like anyone else) aren't getting optimal nutrition.
(When I lightly researched a while ago one of the topics the article you cited considers (correlation of health with weight in normal to overweight interval), I found that there is no consensus and there are studies giving contradictory conclusions. For causation, it's even less clear, and the current position seems to be that weight doesn't have a known causal role if around normal/overweight, instead exercise and diet affect both weight and health.)