What would you give up for an extra year of life?

Investors, economists, traders, and other people may immediately object that the question is under-specified.

Time Preference

At the minimum, they would insist on knowing when they get the extra year and the quality of the year. Let’s assume that the year is a high quality year. Suppose a hypothetical person, currently 50 years old, realistically expected he’d die in 2024. Let’s assume that he is otherwise physically and emotionally healthy. If he could, he would likely pay “a lot” for that extra year.

Now suppose everything else is the same, and the man had the same degree of expectation that he would die in 2054 (thirty years later). Almost certainly he would pay less today for that 31^st year than he would for next year in the first example.

The willingness to pay more for receiving the good (the extra year) now versus later is an example of what economists call time preference. Time preference is a leading reason offered by most economists for the observation that in a free market[1] interest rates are positive (or non-negative).[2]

I have been thinking about the question of the value of extra years of life. You might be surprised by what I’ve learned.

Longevity

I recently finished Outlive, The Science and Art of Longevity by Peter Attia, MD with Bill Gifford.

The book is well-written (except for its habitual use of acronyms that force the reader to constantly flip back to find out what “WHI” or “NNT” or “CGM” or “MUFA” or “SFA” or dozens of other comprehension-destroying acronyms mean), and covers a lot of ground. The implicit promise of the book is that if you take the right actions, you’ll live longer. If that interests you, I recommend the book. I don’t know if it “works” and neither does anyone else. But let’s assume it does.

Is Implementing the Program Worth it?

In this post, I want to address a question that I have not seen addressed anywhere. Namely, is it worth it? That is, is the benefit of following Attia’s program, or a similar exercise program, worth the cost of doing so?

Although the following is an oversimplification, Attia’s hypothesis is that most people can choose behaviors that will maximize their chances of living a long, high-quality life. The majority of the book addresses what Attia has identified as the four largest medical risks for dying: 1) atheroscerlotic disease (heart disease and strokes), 2) cancer, 3) neurodegenerative disease (e.g. Alzheimer’s) and 4) metabolic disease (elevated insulin, fatty liver and type 2 diabetes).

After a couple hundred pages outlining the highlights of what’s known and not known about these diseases, Attia turns to actions we can take — or avoid — that he believes[3] will reduce each of these risks. Attia knows the scientific literature better than most people, and he draws upon his experience treating thousands of patients in his medical practice. Based on this knowledge, he focuses on five areas: exercise, sleep, nutrition, drugs and supplements, and mental health. They are apparently listed in order of their expected efficacy.

In particular, Attia believes that exercise is the most potent action most people can take to extend the quantity of life and improve its quality. He evidently believes it will do both. The second most powerful tool he says is getting enough sleep, which we’ll simplify to 8 hours a night.

For the sake of the following analysis, I’m considering only exercise and sleep.

What Does it Cost?

For most people,[4] the major cost of implementing the “Outlive” program will be time. That’s because Attia recommends a minimum of about 3 hours a week of exercise for beginning exercisers, says he spends 6 hours a week in the gym,[5] and in an episode of his podcast,[6] he (by my count) appears to state that his program requires a total of about 9 hours spread over the week.

If you otherwise wouldn’t exercise and do so because you hope to reap future rewards (i.e. more years of life), from an economic point of view, the hours you spend exercising may be viewed as a cost.[7] However, also from an economic point of view, those hours can be viewed as an investment.[8] We analyze the investment in this post.

We’ll use the range of 3 hours to 9 hours per week as the cost/investment of implementing the exercise portion of the Outlive program.

What’s the Payoff?

The implicit promise of the program is that you’ll live longer. How much longer is an important question, and is difficult to find explicitly addressed.

Attia is 50. The life expectancy for  an American male like Attia, age 50, is 30 years, meaning that his life expectancy is 80.[9] Suppose Attia expects to live to age 88.[10]

Attia is not pulling the extra 8 years out of the air. A 2022 study[11] in the British Journal of Sports Medicine reported that “weightlifting[12]” was associated with a mean extra 9 years of life in its questionnaire-based study of 99,713 adults. The estimated interquartile range[13] of additional years of life was 7.6 years to 10.6 years.

What’s the Return on Investment?

I know there’s a lot more involved in exercising than merely putting in hours. But to keep the analysis tractable, I want to look at the investment “now” of hours into exercise, for the payoff of more years of life “later.”

We can use the standard tools of present value analysis, except the “currency” is hours, not dollars.

Let’s make some base-case assumptions. The most important assumptions are:

1. A 50 year old male who doesn’t exercise can expect to live to age 80
2. That same male who puts in 8 hours per week of exercise can expect to live to age 88.
3. We will measure investment and return in terms of hours per year
4. We assume people value their waking hours, and sleep 8 hours a night. We don’t count the 8 hours of sleep as “return” though you of course could decide to do so.
5. The exercise continues every year, even after age 80
6. The exercise costs only the time allocated to it and provides only the expected extra years of life (i.e. no “disutility” or “utility” except the expected life extension benefit[14] )
7. Everything else is constant

Given these assumptions, we can compute a “rate of return” just as we would with dollars.

When we do so we find that the return on investment is 5.8%.

Sensitivity Analysis

What if we can get 75% of the benefit, i.e. six extra years, by investing only 6 hours per week? In that case, the return is 6.1%.

If 3 hours a week buys four extra years, the return is 6.5%.

Note that these returns are calculated based on guesses. We simply don’t have the data to state with confidence that the assumptions are reasonable. The point of the analysis is that it gives us a “ballpark” return estimate.

Click here to request a table of sensitivity analysis covering hours per week of investment from 3 to 10, and extra years of life from 2 to 10.

Is it a Good Investment?

Each person will obviously have to decide for himself or herself whether the investment of time and effort into an exercise program is a good investment.

There are at least two components to the analysis of any investment. Those two indispensable components are risk, and return.

In the case of exercise extending your life, there is a risk that exercise will not work to extend your life. (We ignore other, mostly minor, risks reportedly associated with beginning an exercise program[15]. The conventional advice is “check with your doctor.” Nothing in this blog post is or should be construed as medical advice.)

With standard financial investing, we usually measure risk in terms of variability of return. We can apply the same concept here, but as we have so little data all we can really do is guess. That’s why we ran a table of sensitivities, to see how the return would vary as the number of extra years varies from few to many.

Let’s say that you, or a client, is comfortable that the expected return on the exercise investment is 6%. Is that good?

If a 6% return sounds low to you, that may be because we’ve been conditioned by a lifetime of living in an inflation-riddled world. In fact, in the investment world, long run real (i.e. inflation adjusted) returns of 6% are very good, by historical standards.[16]

Keep in mind that there’s a whole lot more that’s unknown than is known about the effects of our actions, or inactions, on our life expectancies. Even “facts” often are not. For example, I have long believed that the oldest documented human life ever was that of a French woman named Jeanne Calment, widely believed to have lived to 122. Attia reports this. Ten seconds of search reveals that in 2019 a paper was published[17] claiming that the woman identified as Jeanne Calment was actually her daughter, 23 years younger. If true, the “oldest person ever to live” lived to 99, not 122. I have no idea whether the claim (any of these claims) is true. The point is that even history is hard to grasp, and we must be careful of relying on “facts” that may or may not be so.

History Suggests We Restrain Our Enthusiasm

Longevity is a human desire going back to ancient times, and probably before. If we assume that our ancestors were, for the most part, just as smart as we are,[18] we should not ignore the many failed attempts to develop an art, a science, or a magic of life extension. I believe that history suggests that the prior probability[19] that any particular program or prescription for life extension will work should be low. Here’s why.

The disappointments have been many. In Greek mythology, the goddess Eos (Greek gods and goddesses were said – by Homer among others – to be immortal) had a human lover, Tithonus. She asked Zeus for, and was granted, immortality for Tithonus. She forgot to ask for eternal youth. Oops.

The Gilgamesh poem features an elixir of life.

Medieval alchemists searched, in vain, for the Philosopher’s Stone, one of whose magical properties was the ability to rejuvenate and/or provide eternal life.

Ponce de Leon, a real Spanish explorer, is probably best known for his failed attempt to find the Fountain of Youth, in Florida.

In the 1970s, the desire was reborn as the Life Extension movement, and was associated with alternative medical treatments, such as supplements and vitamins.

I once had a client, now dead, who asked me to do research into having his body frozen, post-mortem, so it could eventually be “reanimated.” This approach was made famous (to the extent it is famous) by the “cryonic suspension” of former Boston Red Sox star Ted Williams.[20]

As far as I know, none of the previous methods of life extension, immortality, rejuvenation, longevity, or call-it-what-you-will has been shown to work.

Will this time be any different?

I hope so. But your guess is as good as mine. The arguments that the interventions should work are persuasive. But that doesn’t mean they’re correct.

My goal here is simply to provide an investment-based perspective on an issue that concerns many people, and seems to have gotten little such attention.

I know this is a bit outside the usual material that we talk about. If you have any thoughts or reactions, I’d greatly appreciate your sharing them with me. You can comment on our blog, email us at [email protected], or call. As always, we’re reachable at (703) 437-9720.

---

[1] The incidents of negative interest rates seen in recent years have occurred only in markets heavily influenced by central banks and governments who imposed negative rates by fiat and/or legal measures.

[2] This understanding of time preference in economics goes back at least as far as 1871, to Austrian Carl Menger’s observation “To the extent that the maintenance of our lives depends on the satisfaction of our needs, guaranteeing the satisfaction of earlier needs must necessarily precede attention to later ones.” Principles of Economics, translation reprinted 2007, Ludwig von Mises Institute, Auburn, p. 153.

[3] Formidable epistemological problems are inherent in a science of human longevity. The “gold standard” of scientific knowledge, reproducible experiments, are not possible (for ethical and practical reasons) in the case of human longevity. Most of what is known, or believed to be known, is inference from animal studies and observational studies in human populations.

[4] Attia says 77% of Americans don’t exercise (p. 218)

[5] https://www.youtube.com/watch?v=ExFMe4fOsUg

[6] https://peterattiamd.com/ama32/

[7] The proper economic definition of cost is what you give up in order to do what you do. This is the opportunity cost theory of cost. See, for example, this explanation of cost by economist Russ Roberts, https://www.econlib.org/library/Columns/y2007/Robertsopportunitycost.html or see this video by the well known economist Tyler Cowan: https://www.youtube.com/watch?v=uorrlWJ23Mg

[8] The economic definition of investment is the voluntary forgoing of a current consumption so that a resource can be instead directed toward activity that is expected to generate a greater future consumption.

[9] https://stacks.cdc.gov/view/cdc/118055                      

[10] Or so I infer from his use of a “life calendar” showing the weeks of his life till age 88. https://honehealth.com/edge/health/dr-peter-attia-longevity-life-calendar/

[11] https://pubmed.ncbi.nlm.nih.gov/36167669/

[12] The compound noun weightlifting is the name of the Olympic sport. Lifting weights as an exercise program not connected with the sport is, properly, weight lifting. I am confident that the article, though it refers to “weightlifting” actually means weight lifting. The photo is of me competing in weightlifting.

[13] I.e. 25% of people gained less than 7.6 years, and 25% of people gained more than 10.6 years. (Recall this is according to the statistics. The study reported associations, not causality.)

[14] By no additional disutility or utility I mean roughly that I am counting only the time used, and that the act of exercising, on its own, produces neither pleasure nor pain nor any cost other than the time expended and no benefit other than expected extra lifespan. This is almost certainly an oversimplification. A more detailed analysis would attempt to incorporate these other costs and benefits. I omit them for reasons of tractability.

[15] https://www.ahajournals.org/doi/full/10.1161/01.CIR.0000075572.40158.77 see “Risk of Physical Activity” section.

[16] See, e.g. https://www.credit-suisse.com/media/assets/corporate/docs/about-us/research/publications/credit-suisse-global-investment-returns-yearbook-2023-summary-edition.pdf

[17] Evidence That Jeanne Calment Died in 1934—Not 1997, REJUVENATION RESEARCH Volume 22, Number 1, 2019. The journal seems to be legitimate, though I lack the knowledge to say so with much conviction.

[18] Considering that among these ancestors were Aristotle, Archimedes, and Newton (who spent more time on alchemy than on physics), it’s hard for me to think that our predecessors were not at least as smart.

[19] Prior probability is an indispensable component of so-called Bayesian statistics. A prior probability is, roughly, your subjective belief in the probability that a given proposition is true (e.g. exercise will make you live longer) before you consider whatever additional information is available.

[20] https://www.cbsnews.com/news/ted-williams-frozen-in-two-pieces/