Thank you, @Louden Wilde. As usual, a very informative post from you!
I mean overall life/health-span (the latter being the the portion of an organisms life in which they are reasonably good health, e.g. mobile, functional). Calorie restriction had been shown to extend life/health span in rats as far back as the 1930s - it has since been shown to work in pretty much every organism tested. Obviously we can't in test this in humans as rigorously as we'd like (i.e. by by going through the whole lifespan), but biomarkers suggest this is the case with us as well. An even better biomarker than telomeres (IMO, and others) is the
epigenetic clock
Note this method can also estimate when
you are likely to die
Interesting to know: I hadn't been aware of this. (Although that's no surprise, given that about the only thing I knew of the genetic aspect of aging was that telomere-length theory, and that because it's so widely covered in the popular 'press'!

)
Evidence is increasing for those other two. When I left academia a few years ago (where I had done some environment/epigenetics work), I spent a year at a biotech working in this area, and so got pretty up on the literature. Just finishing work and frankly don't feel like digging all the refs up right now. Worth noting that these same stressors can have protective effects in other areas: e.g.
Protection against renal ischemia-reperfusion injury through hormesis? Dietary intervention versus cold exposure
Dietary restriction (DR) and fasting (FA) induce robust protection against the detrimental effects of renal ischemia-reperfusion injury (I/RI). Several mechanisms of protection have been proposed, such as hormesis. Hormesis is defined as a life-supporting beneficial effect resulting from the cellular responses to single or multiple rounds of (mild) stress. The cold exposure (CE) model is a stress model similar to DR, and has been shown to have hormetic effects and has proved to increase longevity. CE is considered to be the most robust method to increase metabolism through activation of brown adipocytes. BAT has been considered important in etiology of obesity and its metabolic consequences.
Right, very VERY interesting! (Although TBH there was a great deal there, as well as in the earlier articles, that was much too technical for me to follow; but yeah, the gist was understandable enough.)
I'd been aware of exercise as an important variable affecting longevity (not just indirect effect of exercise on longevity by making your general health better, but by directly affecting your telomere length); but these two also look promising.
As all this applies directly to our lives, personally I'm not about to start taking freezing cold baths any time soon, but the dietary restriction part sounds promising. Not that I'm jumping in to try it just yet! But absolutely, that's something I'm going to make a point of trying to read up a bit more on for now.
Exercising's a ubiquitous thing these days, and there's no reason why one shouldn't think seriously about incorporating the calorie deprivation thing also, properly planned and advised that is, into one's lifestyle. Living longer is an attractive goal!
eta:
Started a
new thread, to specifically discuss the calorie restriction bit.