Friday, August 14, 2015
Calorie Restriction terminology.
This is written in response to a tweet by Razib Khan -- is what americans term "calorie restriction" just eating a normal amount of food proportionate to your activity levels? :-)
(Might be a semi-rhetorical question. Anyway ..)
(These lines were originally written as an intended series of tweets.)
CR - the original version was based on Walford book ~1982 (in response to Pearson and Shaws 1981 Life Extension book.)
As mechanisms-search proliferated, meanings of "CR" expanded (e.g. "CRON", CR with Ordinary Nutrition.)
Informed use of 'CR' is usually about surpassing (species) ~maximum~ life extension. (e.g. 120+ y.o.)
It seems to me an increasingly a small number of commercial promoters and journalists leave the interpretation ambiguous -- ~any~ life extension.
Mechanism theories include that exercise counts toward caloric 'deficit'. (Yes kind of, not exactly).
By the way, saw a very recent paper - every 20 lb.s long term permanent wgt loss - 200 cal. metabolic drop. Plus old observations that obese-prone mice strains benefited from CR most. So a Question: If a 260 lb. person 'strain' loses 60 and stabilizes at 200, is there a CR type benefit? (Yes kind of, not exactly.)
Mechanism explanations appear increasingly 'less wrong'. More detailed and more molecular. Time-to-practical implementation still unclear. Maybe soon. Or not.
(Personal note: I've been a skeptic of life extension efforts applying to humans for a very long time. I suspect it's my background in evolutionary studies and hence an appreciation of biological complexity that makes me so. Lately I'm slightly less skeptical. But note that on the longevity research lists all the proposed currently possible available treatments (various drugs etc.) all have serious risks and downsides.)