Does being skinny help you live longer?

For about 30 years, the consensus of researchers has been that caloric restriction (CR) extends lifespan.

Nematodes, mice, fish, and other animals were studied and the conclusion was that this was the only way to increase longevity.

The evidence was so persuasive that many researchers began to practice caloric restriction (CR) themselves. Millions of dollars of grant money were awarded to researchers who could show that eating less meant living longer.

In 1987 the National Institute on Aging began its landmark study with rhesus monkeys to see if the observed benefits of CR could be extended to primates (i.e. humans). Another, shorter study with rhesus monkeys ran concurrently with another lab in Wisconsin.

The smaller study from Wisconsin excitedly published its results in 2009 and the New York Times splashed the conclusion across the front page: Caloric restriction increases the lifespan of rhesus monkeys! At long last, we could infer that CR in humans would help us live longer.

But there was a problem.

The researchers had a serious bias to contend with. Many of them practiced CR themselves and were depending on funding for their livelihood. The funding wouldn’t continue if their data showed that CR didn’t work. When monkeys died early on CR, they threw out data that didn’t match their preconceived notions of reality and claimed that the deaths were not age-related! It turns out that they threw out half of the data so that the results could get them on the front page of the New York Times.

Two weeks ago, the researchers from the National Institute on Aging sheepishly revealed the results of the larger CR study. After 25 years, the two groups of animals, whether they were starved or fed a normal diet, died at about the same age. Worse yet, even some expected results like cardiovascular health, diabetes, etc. didn’t show up that much different except in males.

As they scratched their heads at the unexpected results, other researchers who had been more critical of the consensus of opinion found that many of the supposedly persuasive rat studies showed that a third of the rats didn’t respond to CR diets at all, but researchers threw out the results because they thought the rats were somehow abnormal.

Perhaps most compelling is that researchers can allow themselves to be so biased, and this affects their studies negatively. Anthropogenic global warming, anyone?

For a great article on the above, see this article.

Also, here’s the story from the New York Times. Article

As for me? I’ve long said that because the body wants to maintain homeostasis, attempting to change that dramatically is usually fruitless, and perhaps harmful.

Exercise is far more healthful in my opinion than restricting your diet. You may not lose weight, but you will be healthier in the long run. People who do both are admirable, but it really is a catabolic process (i.e. breaking down) and in my opinion, unless done in moderation, typically results in problems.

Also, any sustained exercising at your target heart rate longer than one hour is probably not beneficial.


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