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Comment by badfrog | Hacker News Reader

From the intro, why this is interesting:

> The question of whether mean body temperature is changing over time is not merely a matter of idle curiosity. Human body temperature is a crude surrogate for basal metabolic rate which, in turn, has been linked to both longevity (higher metabolic rate, shorter life span) and body size (lower metabolism, greater body mass).

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> Human body temperature is a crude surrogate for basal metabolic rate

> higher metabolic rate, shorter life span

> lower metabolism, greater body mass

In other words, if you are a really, really skinny person (like myself), you would be looking at a statistically shorter lifespan, unless somehow your normal body temp is lower than average or you spot some other sign of decreased basal metabolic rate. Huh!

I had some intuition along those lines but thought it’s false, and habitually viewed high metabolic rate as nothing but a “feature” until now.

I suppose, then, you might want to be aware of this if you have a young family—get life insurance, if you haven’t already (and I also hope, if this research proves sound, insurers won’t start taking it into account any time soon).

> if you are a really, really skinny person (like myself), you would be looking at a statistically shorter lifespan, unless somehow your normal body temp is lower than average or you spot some other sign of decreased basal metabolic rate. Huh!

I think you are making the error of combining the "folk" understanding of high metabolism - that you are skinny, with the scientific understanding of high metabolism, which means you expend a lot of calories every day. It's more likely that you have calorically restricted yourself throughout your life to become skinny, which has longevity benefits, and it's also likely that very fat people burn a lot of calories every day - high metabolism, worse for longevity.

My fundamental question on calorie restriction is that women have been doing it for superficial reasons for quite a while, but women's superior life expectancy seems soley due to high risk behavior by men when they are young and middle age.

I've never seen anything testing that hypothesis.

There are actuary tables of average life expectancy given a base age. If you are a 70 yo female, you’re expected to live 2 years more than a 70 yo male.

https://www.ssa.gov/oact/STATS/table4c6.html

It’s possible this difference is a legacy from riskier makes behavior in middle age. I can’t think of a reasonable way to control for this though. Maybe look cross culturally to see if the effect is stable with respect to different male behavior norms?

> If you are a 70 yo female, you’re expected to live 2 years more than a 70 yo male.

The difference is still a year at 86, and doesn't fall to par until supercentenarians.

I wonder how much of that is driven by suicide. Older men commit suicide at much higher rates than older women:

https://en.wikipedia.org/wiki/Epidemiology_of_suicide#/media...

2 years for 40% reduction in daily calories? No fucking thank you.

You know what blows away the actuarial tables for life expectancy? Exercise. That makes your life better for longer, much more than starving yourself.

> I've never seen anything testing that hypothesis.

Actuarial tables would tell you.

Though there would also be confounding variables e.g. previous "at risk" behaviour could still be in effect.

>women have been doing it for superficial reasons

could you list those reasons for us?

Don’t know why this is getting downvoted. The parent statement is news to me and I would definitely like to see some sources.

it's pretty obvious it's the hackernews patriarchal bubble. men seem to think they know everything about women, and anyone questioning that is put in their place.

FWIW, I would be interested in hearing why you disagree. I think some of the downvotes probably came because the reasons behind the original statement seem very obvious (there is and has been a lot of social pressure on women to look thin; appearance is commonly referred to as a 'superficial' characteristic), so asking for a list instead of just responding to the obvious interpretation can come across as disingenuous.

I don't think asking for clarification on an ambiguous statement is disingenuous, but I'm willing to listen to why you think that.

I said it can come across as disingenuous, largely because the original statement didn't seem ambiguous to me, nor I suspect to the people who downvoted you. And sometimes people pretend not to have understood something, as a way to indirectly criticize it without having to get specific or engage directly. The topic being potentially a controversial one (relating to gender), it seemed like you might have been hinting that the statement was sexist without actually saying why. But I don't know what your actual intent was. (And I'm still not sure whether you have a disagreement with the main substance, i.e. you doubt there would be a relevant difference in prevalence of calorie restriction in men and women, or you think the use of 'superficial' was disrespectful, or something else.)

not because of the inquiry itself, wich seems valid, but because the way it's posed, which suggests it's just a bait for grandstanding

"but women's superior life expectancy seems soley due to high risk behavior by men when they are young and middle age"

huh?

Work, motorcycles, sports, car accidents, ...

But fit people live longer, and high intensity exercise seems to increase DNA repair and antioxidants (the high oxidation of exercise seems to be managed by antioxidant processes kicking into gear, which overcompensate for oxidation versus a sessile person from what I've read... casually)

> In other words, if you are a really, really skinny person (like myself), you would be looking at a statistically shorter lifespan, unless somehow your normal body temp is lower than average or you spot some other sign of decreased basal metabolic rate. Huh!

It would also depend whether your skinnyness is metabolic or nutritional (aka do you eat a lot and burn it easily, or eat little / low-calorie stuff).

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