Feb. 5, 2003 -- Too many fat people are roaming this nation, bu
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.
Oh Yes They Can
Get a grip -- willpower has much to do with it, says James O. Hill, PhD, director of the Center for Human Nutrition at the University of Colorado Health Sciences Center in Denver.
Hill analyzed national data on obesity in American adults, which shows that 65% of adults are overweight, compared with 56% in 1994.
"We found that people are gaining one to two pounds a year," Hill tells WebMD. "We're only eating a tiny amount more every day than we should -- no more than 100 calories more. But we're storing about 50 extra calories a day, on average."
The solution is simple -- "eat less," says Hill. More specifically, cut 100 calories every day. "It means leaving a few bites of hamburger, putting the cookie down," he says. "Not much more than that."
Then, find time for 15 minutes of walking every day. That equals 2,000 steps, says Hill. One foot in front of the other -- brisk, slow, whatever pace feels right to you.
"These are tiny changes," Hill tells WebMD. "We've tried to get people to make total makeovers of life, but they don't stick with it. But these are small changes that are sustainable."
But -- his formula won't make you lean, he admits. Here's the upside: "If you're overweight, you won't get any more overweight."
In fact, his strategy is being tried in Denver with success. "So far, it's working wonderfully. Anybody can do it."
"Obviously, genetics plays a huge role in body weight," Hill admits. "That's why some people won't ever be thin. And this obesity epidemic -- we understand so little about it. Of course we don't disagree. There's definitely a genetic component to weight gain. If we both eat 100 calories, I may store 80 calories, you may store 60. But if each of us ate a little less, neither one of us would gain weight."
