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Comment by nostrademons | Hacker News Reader

Assuming you're not on drugs or thinking of killing yourself, you're probably not in the cohort that's dragging the life expectancy stats down.

Life expectancy is a weighted average (no pun intended), and so it's unusually sensitive to outliers. People who die early drag the average down much more than people who live close to the mean life expectancy. The biggest premature killers of Americans are obesity, drugs, car accidents, and suicide. Anything that addresses one of those causes of death has an outsize effect on life expectancy. There are 100M+ obese Americans. There are about 100,000 overdose deaths per year. Obesity, while not as lethal as drugs or suicide, afflicts 1000x as many patients, and so a treatment for it can have a large effect on the numbers.

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> The Oxford University research found that moderate obesity, which is now common, reduces life expectancy by about 3 years, and that severe obesity, which is still uncommon, can shorten a person's life by 10 years. This 10 year loss is equal to the effects of lifelong smoking.

https://www.ox.ac.uk/news/2009-03-18-moderate-obesity-takes-...

> According to the CDC, 9.4% of adults in the United States were severely obese between August 2021 and August 2023. This is higher for women (12.1%) than men (6.7%). The prevalence of severe obesity varies by age group, with the highest rates in adults aged 40–59 (12.0%)

Only 9.4% of people are severely obese. Moderately obese people have only a ~4% shorter life-span than healthy weight individuals - much of which can probably be attributed to other lifestyle issues besides simply being overweight.

This will move the needle, but I doubt as much as you think.

There's a lot more smokers than there are severely obese people.

>There's a lot more smokers than there are severely obese people.

Huh, I was going to argue this, but you're right (in the US). 19.5% of the population smokes, so there's about twice as many smokers as severely obese people.

I was sure it had dropped to 5-10%. I guess I'm in a bubble (of fresh air).

Kind of a tangent but I think a big part of the explanation for declining life expectancy is hiding here in plain sight.

Since everyone knows smoking is bad for a long time now, we’re going to eventually need to categorize stuff like lung-cancer as a death of despair, similar to other deaths caused by alcoholism, opioids, or suicide.

A lot of people who otherwise might quit smoking are probably looking at impossible dreams of home ownership or retirement, and thinking consciously or unconsciously that there is more dignity in a death at 50-60ish than one at 80ish when you’re unemployable and the thin promises of social safety nets have fallen through.

Smoking (or other high risk activities) might be a dirty habit but it’s still more socially acceptable than suicide.

That's a bleak view. I doubt a substantial percentage of smokers are smoking specifically to die sooner.

Most of them are smoking primarily because they're addicted.

A few of them actually like smoking.

Dying sooner is certainly not why they started.. rather the bleakness of outlook is a (fairly rational) reason why they don’t quit.

If obesity is supposed to be the other main candidate for why life expectancy is down, you can do a similar analysis there. Is life really good enough to prolong or attempt to improve for people that are in at-risk categories? That’s the question people are looking at when they choose to move towards or away from self-care. For someone who makes minimum wage and already has to choose between paying for a date or paying for rent, it makes less sense for them to care much about losing weight, because it makes a bad life longer but won’t help their love life.

This is how practically all population-level analysis of health is just economics in disguise, even without directly looking at costs of medicine/services

I think your hypothesis is correct but your reasoning is wrong. Few people are morbid enough to think "Oh my life sucks so why bother looking after myself". But if you're constantly stressed because you're struggling in life, small indulgences like smoking, alcohol and fast food/sugar are a lot harder to resist as they provide a much needed outlet/release.

It would be really interesting to see a stat that is like… “life expectancy without morbidities that can be avoided with some effort.”

Which, I recognize is a pretty privileged way of putting it—people struggle with weight, mental health, and drugs, and those are real struggles that shouldn’t be ignored. I just also want to see where things are developing on the upper-bound for reasonably plausible lifespans.

>Life expectancy is a weighted average

Sure, if all the weights are 1. Where i come from, we just call that an average.

>People who die early drag the average down much more than people who live close to the mean life expectancy.

This is true of all averages where all weights are the same.

I should probably have said the change in life expectancy is a weighted average, weighted by how far you are from the average. If average life expectancy is 80, removing a data point where somebody died at 40 has 8x the effect of removing a data point where somebody died at 75.

In case anyone else is curious about the specific term for the concept you are describing, it's https://en.wikipedia.org/wiki/Leverage_(statistics)

(To reproduce exactly the scenario being discussed, you fit a constant-only model to the data using least squares: that gives the average as the best fit. Then, you measure the leverage of each point of interest.)

Ok, that makes a lot more sense in light of your argument!

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