Fighting Fat Is an Uphill Battle, Experts Say
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By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - Just take three fewer bites of that burger and you will stop gaining weight. Or walk an extra mile every day -- and going up and down the stairs counts.
It sounds easy to lose weight. But as the sobering statistics show, it is more easily said than done.
Most people with growing girths -- and it is a worldwide problem -- will in the end be unable to overcome biology and lose much weight unless some big changes occur in society, experts agreed on Thursday.
"Maybe the answer is, in part, reducing our expectations," said Jeffrey Friedman of the Howard Hughes Medical Institute at Rockefeller University in New York.
More than 60 percent of Americans are overweight.
And more than 30 percent of Americans are obese, meaning they carry so much extra weight that their health is at real risk. Obesity can lead to diabetes, heart disease and some forms of cancer.
Worldwide, more than 300 million people are obese, according to the World Health Organization (news - web sites).
In a special issue of the journal Science devoted to obesity, several experts agreed that a consumer-oriented society and technology that encourages people to exercise less is conspiring with genetics to make people fatter.
"The U.S. food supply provides 3,800 kilocalories (calories) per person per day, nearly twice as much as required by many adults," wrote Marion Nestle, chair of the Department of Nutrition and Food Studies at New York University.
That means companies in the food business have to compete for market share -- which they do by advertising more, targeting children, making health claims and offering more "value for money" in the form of larger portions.
"Food marketing promotes weight gain," Nestle wrote.
JUST WALK IT OFF
But we can just walk it off, argues James Hill of the University of Colorado Health Sciences Center. "It would take most people only 15 to 20 minutes total to walk an additional miles each day," Hill and colleagues wrote in their report.
Hill's team used national survey data to figure out that Americans had gained, on average, 14 to 16 pounds (6.3 to 7.3 kg) each over eight years.
Figuring that each pound (half a kg) equals about 3,500 calories, and that the body stores about half of the calories its consumes as fat, they decided that eating 100 fewer calories a day, or burning off 100 more calories a day, would be enough to stop that steady weight gain.
"Something around 100 calories a day is doable," Hill said, adding that 100 calories equals a mile of walking or running, or three bites of a hamburger.
But Friedman, best known for his discovery of the fat hormone leptin, said the body will do its best to compensate and sabotage even this modest effort.
"I don't want to tell you not to try. There is no question that losing weight in many can improve health, as can becoming fit," Friedman said in a telephone interview.
And he said, it should be within most people's reach to lose 10 pounds (5 kg). But it will not be easy.
"The problem is that people are not capable of moderating, unconsciously, their caloric intake," he said.
"The basic system that regulates weight adjusts your intake upwards to compensate for the calories you burn," he added. "It's not so simple as telling someone all you need to do is eat 100 fewer calories than you burn."
The body has evolved a powerful and complex hormonal system aimed at keeping weight on. "That's what obese people are up against when they are trying to lose substantial amounts of weight," he said. "They are being thwarted by this metabolic system whose job is to resist substantial changes in weight."
The answer? More research -- into diets that work, perhaps into safer diet drugs, Friedman said.
"If we wait for Jeff's approach, we'll all be obese in a few years," Hill said in a telephone interview. "We have got to stop the weight gain now. What we are doing now isn't working."
Nestle and Hill also advocate changes that will help people exercise more and eat healthier food -- including better labeling of food to tell people exactly how many calories they are eating. "Maybe we need labels like the labels on cigarettes," Hill said. |
