The trouble with this sort of recommendation is that it would take a large-sample double-blind longitudinal study to generate even weak evidence that the proposal actually increases longevity, and performing such studies isn’t remotely feasible. So instead people are tempted to adopt lifelong ‘longevity’ programs based on speculation and studies that are too weak to generate any meaningful weight of evidence. Rationally, the expected return on investing time in such programs is severely negative—you’ll defintely invest significant time and energy trying it out, and the odds of hitting something that works by pure chance (which is all you’re really going on) is infintesimal.
For instance, this ‘paleo diet’ business relies on the idea that eating the same thing our ancestors did in 10,000 BC will make us live longer. But our ancestors lived much shorter lives than we do, we have only weak evidence about what they ate, and anyway 600 generations is more than enough time for evolution to re-tune the human digestive system. So we’re left with no particular reason to think this idea is even worth investigating, let alone that the specific recommendations will accomplish anything.
The trouble with this sort of recommendation [low- carb and paleo diets] is that it would take a large-sample double-blind longitudinal study to generate even weak evidence that the proposal actually increases longevity, and performing such studies isn’t remotely feasible.
This is not true at all, and blindly worshipping the double-blind study like this will prevent you from learning anything. Dietary studies, with few exceptions, cannot be blind since people know what they’re eating. But people can easily observe what effects diets have on them, as long as they’re keeping the right quantitative data. Weight isn’t the right variable to be tracking, since it can’t distinguish fat from muscle, and many studies went astray that way. But tracking exercise reps, body fat percentage, energy levels and various interesting blood tests are all feasible, useful and actually done. A simple observational study plus an understanding of biochemistry is sufficient to justify a dietary preference, so long as certain known traps are avoided.
I won’t mix claims about the goodness or badness of particular diets in here, but I’d like to say that the questions are answerable, and some diets are better than others in general. Individual biochemistries vary in ways that interact with possible diets, but those interactions can be understood, and many of them are understood, so it’s wrong to point to individual differences as though they make diet inherently mysterious.
Obesity correlates with several chronic diseases, and so body fat percentage must as well. There are certain diseases where elevated risk is directly associated with fat specifically (I remember seeing something where heart disease is affected by abdominal fat in particular) so at least sometimes fat matters, and not just mass.
Note that it doesn’t necessarily imply any kind of causality.
I think “health” is a nebulous concept anyway—in my book, you are “healthy” if the physical state of your body allows you to do what you want to do.
The trouble with this sort of recommendation is that it would take a large-sample double-blind longitudinal study to generate even weak evidence that the proposal actually increases longevity, and performing such studies isn’t remotely feasible.
This is simply not so. If specific studies show improved longevity from specific dietary changes, it is quite reasonable to infer combining multiple specific beneficiary changes will also result in a benefit.
Skepticism is warranted, but the idea that eating whatever you want is actually better for your longevity is just bogus.
There is no control group. The hypothetical diet/lifestyle of our evolutionary ancestors is the closest to a control, but it no longer exists.
You need to pick what experimental group you want to be in.
For instance, this ‘paleo diet’ business relies on the idea that eating the same thing our ancestors did in 10,000 BC will make us live longer.
Yes, because of a mountain of specific evidence which supports this hypothesis (omega 3, sodium, vitamin D, reduced calories, more fruits/veggies, etc etc)
But our ancestors lived much shorter lives than we do,
On average, yes. But based on what we know from hunter-gatherer tribes, a fraction probably lived to ripe old age, and these luckier/healthier specimens would tend to have more offspring. Regardless, just because we have eliminated most of their causes of death does not mean we have not also reduced our health in other ways.
we have only weak evidence about what they ate
Not really. We have reasonably good ideas about what they ate.
and anyway 600 generations is more than enough time for evolution to re-tune the human digestive system.
This is not a great length of evolutionary time, although it is enough for some strong selection effects for neotany changes such as prolonging lactase production and increased robustness for ceral grains. Nobody is saying that we don’t have some neolithic adaptations—of course we do. But that doesn’t mean they have had enough time to hit equilibria, or those equilibria are optimal for longevity.
Also, some of the more profound effects are far more recent, such as the omega 6 shift, artificial illumination, and sunblock which have occured in just a handful of generations—a blink of an eye.
For instance, this ‘paleo diet’ business relies on the idea that eating the same thing our ancestors did in 10,000 BC will make us live longer.
Not quite. It’s based on the idea that eating a specific list of foods will make us live longer. The bit about that being what ancient humans ate is probably both untrue and irrelevant, but we have direct data on the effects of the specific foods, so the existence of an additional, invalid argument which has gotten undue attention should not affect our judgment.
What part about “what ancient humans ate is probably both untrue and irrelevant”? I mean we don’t know exactly what range of foods they ate, but we have pretty good ideas.
The important point here is that the evolutionary diet/lifestyle theory correctly predicted a large swath of specific effects, now validated. Undue attention? You might as well argue against evolution.
Always keep in mind that you may see improvements in health outcomes simply from being the kind of person who deliberately starts a diet she believes is healthy. (The same phenomenon that makes all kinds of education experiments perform well because the most motivated parents and children sign up.)
The trouble with this sort of recommendation is that it would take a large-sample double-blind longitudinal study to generate even weak evidence that the proposal actually increases longevity, and performing such studies isn’t remotely feasible. So instead people are tempted to adopt lifelong ‘longevity’ programs based on speculation and studies that are too weak to generate any meaningful weight of evidence. Rationally, the expected return on investing time in such programs is severely negative—you’ll defintely invest significant time and energy trying it out, and the odds of hitting something that works by pure chance (which is all you’re really going on) is infintesimal.
For instance, this ‘paleo diet’ business relies on the idea that eating the same thing our ancestors did in 10,000 BC will make us live longer. But our ancestors lived much shorter lives than we do, we have only weak evidence about what they ate, and anyway 600 generations is more than enough time for evolution to re-tune the human digestive system. So we’re left with no particular reason to think this idea is even worth investigating, let alone that the specific recommendations will accomplish anything.
This is not true at all, and blindly worshipping the double-blind study like this will prevent you from learning anything. Dietary studies, with few exceptions, cannot be blind since people know what they’re eating. But people can easily observe what effects diets have on them, as long as they’re keeping the right quantitative data. Weight isn’t the right variable to be tracking, since it can’t distinguish fat from muscle, and many studies went astray that way. But tracking exercise reps, body fat percentage, energy levels and various interesting blood tests are all feasible, useful and actually done. A simple observational study plus an understanding of biochemistry is sufficient to justify a dietary preference, so long as certain known traps are avoided.
I won’t mix claims about the goodness or badness of particular diets in here, but I’d like to say that the questions are answerable, and some diets are better than others in general. Individual biochemistries vary in ways that interact with possible diets, but those interactions can be understood, and many of them are understood, so it’s wrong to point to individual differences as though they make diet inherently mysterious.
Is body fat percentage a good surrogate for health?
Obesity correlates with several chronic diseases, and so body fat percentage must as well. There are certain diseases where elevated risk is directly associated with fat specifically (I remember seeing something where heart disease is affected by abdominal fat in particular) so at least sometimes fat matters, and not just mass.
Note that it doesn’t necessarily imply any kind of causality.
I think “health” is a nebulous concept anyway—in my book, you are “healthy” if the physical state of your body allows you to do what you want to do.
This is simply not so. If specific studies show improved longevity from specific dietary changes, it is quite reasonable to infer combining multiple specific beneficiary changes will also result in a benefit.
Skepticism is warranted, but the idea that eating whatever you want is actually better for your longevity is just bogus.
There is no control group. The hypothetical diet/lifestyle of our evolutionary ancestors is the closest to a control, but it no longer exists.
You need to pick what experimental group you want to be in.
Yes, because of a mountain of specific evidence which supports this hypothesis (omega 3, sodium, vitamin D, reduced calories, more fruits/veggies, etc etc)
On average, yes. But based on what we know from hunter-gatherer tribes, a fraction probably lived to ripe old age, and these luckier/healthier specimens would tend to have more offspring. Regardless, just because we have eliminated most of their causes of death does not mean we have not also reduced our health in other ways.
Not really. We have reasonably good ideas about what they ate.
This is not a great length of evolutionary time, although it is enough for some strong selection effects for neotany changes such as prolonging lactase production and increased robustness for ceral grains. Nobody is saying that we don’t have some neolithic adaptations—of course we do. But that doesn’t mean they have had enough time to hit equilibria, or those equilibria are optimal for longevity.
Also, some of the more profound effects are far more recent, such as the omega 6 shift, artificial illumination, and sunblock which have occured in just a handful of generations—a blink of an eye.
Not quite. It’s based on the idea that eating a specific list of foods will make us live longer. The bit about that being what ancient humans ate is probably both untrue and irrelevant, but we have direct data on the effects of the specific foods, so the existence of an additional, invalid argument which has gotten undue attention should not affect our judgment.
What part about “what ancient humans ate is probably both untrue and irrelevant”? I mean we don’t know exactly what range of foods they ate, but we have pretty good ideas.
The important point here is that the evolutionary diet/lifestyle theory correctly predicted a large swath of specific effects, now validated. Undue attention? You might as well argue against evolution.
Always keep in mind that you may see improvements in health outcomes simply from being the kind of person who deliberately starts a diet she believes is healthy. (The same phenomenon that makes all kinds of education experiments perform well because the most motivated parents and children sign up.)