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First Article
Biology vs. Willpower: Is Fat Due to Our Food or Our Genes?
By Jeanie Lerche Davis
Feb. 5, 2003 -- Too many fat people are roaming this nation, but who -- or what -- is to blame? Is it the genes we inherited or that one extra cookie a day?
Two researchers square off in this week's Science, addressing why more than 60% of Americans are overweight.
Fat People Can't Help It
In one corner: Jeffrey M. Friedman, with the Howard Hughes Medical Institute of Rockefeller University. He says that obesity is not a personal failing -- that we're fighting a battle against biology when we try to stay slim.
The complex mechanism that regulates our weight -- triggering a calorie burn rather than fat storage -- is largely controlled by our genes, says Friedman.
A key element is the hormone leptin, which is produced by stored fat, he writes.
It's a vicious cycle. When we have less body fat, we have decreased leptin levels, which make us want to eat more -- yet reduces the amount of calories burnt. It's this "potent" cycle that that makes successful dieting so difficult, writes Friedman. "A primal hunger trumps the conscious desire to be thin."
Yet this natural weight-regulation system works quite well in all but a small percentage of people, he says. In fact, the huge increase in massively obese people "strongly" suggests the possibility that there are people with a predisposition to obesity -- while others are relatively resistant.
The so-called "thrifty gene" -- inherited from hunter-gatherer ancestors -- predisposes many people to obesity because they tend to store fat for survival in times of famine, says Friedman.
However, those who descended from the Fertile Crescent peoples of the Tigris-Euphrates rivers -- or Western societies in more recent times -- have less risk of starvation, and therefore don't have a tendency to store fat. However, when we do become obese, we likely are "weeded out" by natural selection -- our bad health causes early death.
"Might it be that the obese carry the "hunger-gatherer" genes and the lean carry the "Fertile Crescent" or "Western" genes?" asks Friedman.
First Article
Biology vs. Willpower: Is Fat Due to Our Food or Our Genes?
By Jeanie Lerche Davis
Feb. 5, 2003 -- Too many fat people are roaming this nation, but who -- or what -- is to blame? Is it the genes we inherited or that one extra cookie a day?
Two researchers square off in this week's Science, addressing why more than 60% of Americans are overweight.
Fat People Can't Help It
In one corner: Jeffrey M. Friedman, with the Howard Hughes Medical Institute of Rockefeller University. He says that obesity is not a personal failing -- that we're fighting a battle against biology when we try to stay slim.
The complex mechanism that regulates our weight -- triggering a calorie burn rather than fat storage -- is largely controlled by our genes, says Friedman.
A key element is the hormone leptin, which is produced by stored fat, he writes.
It's a vicious cycle. When we have less body fat, we have decreased leptin levels, which make us want to eat more -- yet reduces the amount of calories burnt. It's this "potent" cycle that that makes successful dieting so difficult, writes Friedman. "A primal hunger trumps the conscious desire to be thin."
Yet this natural weight-regulation system works quite well in all but a small percentage of people, he says. In fact, the huge increase in massively obese people "strongly" suggests the possibility that there are people with a predisposition to obesity -- while others are relatively resistant.
The so-called "thrifty gene" -- inherited from hunter-gatherer ancestors -- predisposes many people to obesity because they tend to store fat for survival in times of famine, says Friedman.
However, those who descended from the Fertile Crescent peoples of the Tigris-Euphrates rivers -- or Western societies in more recent times -- have less risk of starvation, and therefore don't have a tendency to store fat. However, when we do become obese, we likely are "weeded out" by natural selection -- our bad health causes early death.
"Might it be that the obese carry the "hunger-gatherer" genes and the lean carry the "Fertile Crescent" or "Western" genes?" asks Friedman.