I remember that there is a considerable benefit for mice (not a week), but no good evidence for people. On the other hand, there is lots of evidence about correlation of weight with all sorts of diseases, which themselves kill.
I remember that there is this resource called Wikipedia. So I look up Calorie Restriction. I find there’s a very detailed research summary there.
On primates, it starts out with this:
“A study on rhesus macaques, funded by the National Institute on Aging, was started in 1989 at the University of Wisconsin-Madison. This study showed that caloric restriction in rhesus monkeys blunts aging and significantly delays the onset of age related disorders such as cancer, diabetes, cardiovascular disease and brain atrophy. The monkeys were enrolled in the study at ages of between 7 and 14 years; at the 20 year point, 80% of the calorically restricted monkeys were still alive, compared to only half of the controls....”
The section on negative effects talks mainly about what happens when nutrition is poor, or when calories are too low to sustain life. My favorite: “A calorie restriction diet can cause extreme hunger that may lead to binge eating behaviour.” Uh-huh. Every guide on CR I’ve read counsels taking a gradual approach, to give your body time to adjust, and people on CR diets often report that the feelings of hunger attenuate.
The so-called CRON approach (“Calorie Restriction with Optimal Nutrition”) focuses on preventing malnutrition, as you’d expect from the name, and is decidely not “starvation”, which is obviously an eventually terminal condition.
There is promising, but inconclusive, evidence for a positive effect with human beings. If it works well for monkeys, yeast, fruit flies, nematodes and mice, it’s hard to see why it wouldn’t work for human beings. But human beings are exceptional in a number of ways, so I suppose it’s possible it doesn’t work for us.
But human beings are exceptional in a number of ways, so I suppose it’s possible it doesn’t work for us.
Indeed. Most mammals tend to have roughly the same number of heartbeats in a lifespan; short-lived mammals such as mice have much faster heartbeats than long-lived mammals such as elephants. Nearly every mammal on the planet (except those that hibernate) has a lifespan of about one billion heartbeats, give or take a few hundred million here and there.
Humans have a lifespan of two billion heartbeats.
Compared to other mammals, we already have a greatly enhanced lifespan. It’s quite possible that whatever switch calorie restriction turns on in mice, humans already have turned on by default.
It’s quite possible that whatever switch calorie restriction turns on in mice, humans already have turned on by default.
This is, incidentally, the exact same argument David Brin gave me. (He also argued that if CR/IF really worked, we ought to know already based on millennia of religious practices that imply CR/IF and said communities’ intense interest in health matters such as herbal remedies.)
I thought that mild “obesity” (BMI 25) was associated with lower lethality rates than being thin (due to thin people dying more easily when sick; apparently that body fat actually does do its required job sometimes). Normal weight is probably still better, but is that what CR gets you?
Actually, the lower death rates with moderate rather than lower BMI, was an early claim and was later shown to be the result of people being thinner as the result of previously undiagnosed illnesses. I don’t remember the source, as I have read several books on the subject, I sort of think it was from Fumento’s “The Fat of the Land”, but it could have been several others (none of which supported the superiority of moderate over lower BMI, until you get down to starvation levels, ie BMI of less than 18).
Looking at mortality rates in the general population broken down by BMI gives a poor guide to the effects of dietary energy restriction—since many people get thin through being sick or malnourished.
A fairly typical study on the topic:
“How Much Should We Eat? The Association Between Energy Intake and Mortality in a 36-Year Follow-Up Study of Japanese-American Men”
You are probably right, hence the disclaimer that it’s unchecked memory. There clearly must be some unknown point after which the diet starts to kill you, and this point may be very human-specific.
I remember that there is a considerable benefit for mice (not a week), but no good evidence for people. On the other hand, there is lots of evidence about correlation of weight with all sorts of diseases, which themselves kill.
I remember that there is this resource called Wikipedia. So I look up Calorie Restriction. I find there’s a very detailed research summary there.
On primates, it starts out with this:
“A study on rhesus macaques, funded by the National Institute on Aging, was started in 1989 at the University of Wisconsin-Madison. This study showed that caloric restriction in rhesus monkeys blunts aging and significantly delays the onset of age related disorders such as cancer, diabetes, cardiovascular disease and brain atrophy. The monkeys were enrolled in the study at ages of between 7 and 14 years; at the 20 year point, 80% of the calorically restricted monkeys were still alive, compared to only half of the controls....”
The section on negative effects talks mainly about what happens when nutrition is poor, or when calories are too low to sustain life. My favorite: “A calorie restriction diet can cause extreme hunger that may lead to binge eating behaviour.” Uh-huh. Every guide on CR I’ve read counsels taking a gradual approach, to give your body time to adjust, and people on CR diets often report that the feelings of hunger attenuate.
The so-called CRON approach (“Calorie Restriction with Optimal Nutrition”) focuses on preventing malnutrition, as you’d expect from the name, and is decidely not “starvation”, which is obviously an eventually terminal condition.
There is promising, but inconclusive, evidence for a positive effect with human beings. If it works well for monkeys, yeast, fruit flies, nematodes and mice, it’s hard to see why it wouldn’t work for human beings. But human beings are exceptional in a number of ways, so I suppose it’s possible it doesn’t work for us.
Indeed. Most mammals tend to have roughly the same number of heartbeats in a lifespan; short-lived mammals such as mice have much faster heartbeats than long-lived mammals such as elephants. Nearly every mammal on the planet (except those that hibernate) has a lifespan of about one billion heartbeats, give or take a few hundred million here and there.
Humans have a lifespan of two billion heartbeats.
Compared to other mammals, we already have a greatly enhanced lifespan. It’s quite possible that whatever switch calorie restriction turns on in mice, humans already have turned on by default.
This is, incidentally, the exact same argument David Brin gave me. (He also argued that if CR/IF really worked, we ought to know already based on millennia of religious practices that imply CR/IF and said communities’ intense interest in health matters such as herbal remedies.)
That’s where I got my argument from, actually.
There is evidence of benefit for non-human primates.
I thought that mild “obesity” (BMI 25) was associated with lower lethality rates than being thin (due to thin people dying more easily when sick; apparently that body fat actually does do its required job sometimes). Normal weight is probably still better, but is that what CR gets you?
Actually, the lower death rates with moderate rather than lower BMI, was an early claim and was later shown to be the result of people being thinner as the result of previously undiagnosed illnesses. I don’t remember the source, as I have read several books on the subject, I sort of think it was from Fumento’s “The Fat of the Land”, but it could have been several others (none of which supported the superiority of moderate over lower BMI, until you get down to starvation levels, ie BMI of less than 18).
Looking at mortality rates in the general population broken down by BMI gives a poor guide to the effects of dietary energy restriction—since many people get thin through being sick or malnourished.
A fairly typical study on the topic:
“How Much Should We Eat? The Association Between Energy Intake and Mortality in a 36-Year Follow-Up Study of Japanese-American Men”
http://biomed.gerontologyjournals.org/cgi/content/full/59/8/B789
You are probably right, hence the disclaimer that it’s unchecked memory. There clearly must be some unknown point after which the diet starts to kill you, and this point may be very human-specific.
I don’t know about CR, but I’ve done IF (intermittent fasting) for months at a time while maintaining my normal body weight.