Experts Weigh the New Evidence Giving Nature an Edge in the Battle of the Bulges

Inside the peach-colored walls of the pricey Fifth Avenue Clini-Fast Center, weeks are measured in pounds, not days, and the latest clothes described by size, not style.

Weight is a national preoccupation, says clinic director Diane Britton, who once carried 200 pounds on her delicate 5-foot 7-inch frame before losing 60 on a starvation diet of grapefruit and rice. She now dispenses psychological counseling to dieters along with 525 calories a day in the form of chocolate or vanilla milkshakes.

“I will tell you why,” she said recently, adjusting a fun-house mirror in her office that slims and elongates would-be clients.

“When you’re fat, losing weight is the most important thing in life.”

Yearly Tab: $500 Million

An estimated $500 million is spent each year in the United States on obesity research as scientists attempt to settle an age-old dispute over nature vs. nurture.

Are some people born fat or are they conditioned to be fat from birth by a culture that uses food as a reward and views sugar with a passion?

Studies conducted 20 years ago in the United States indicated that children of two obese parents had an 80% chance of also being obese, while children whose parents were of normal weight had only a 14% chance.

“We always knew obesity ran in families, but we didn’t know why,” said Dr. Albert Stunkard, a professor of psychiatry at the University of Pennsylvania who has been considered a leading researcher of fat for decades.

“No one knew for sure if obesity ran in families because of physical heredity or because the children were raised in an environment that fostered fat.”

Most early researchers argued the latter, conducting studies that indicated many overweight people ate to overcome depression and that others were raised in homes where they were fed a steady diet of fatty and sugary food.

But in the last few years, the psychiatrists who conducted the bulk of obesity research have been joined by molecular biologists and chemists whose new studies indicate that there are specific inherited physical traits that can cause some people to gain weight more quickly, and lose it more slowly, than others.

Switch to Heredity

“I’d say there’s been a fairly dramatic change recently from viewing obesity as bad eating habits from childhood to seeing an emphasis on biological factors that can be inherited, including some that manifest as behavioral factors,” said Stunkard in a recent interview. “It appears both nature and nurture play a role.”

The new biological research may someday provide an answer for obese people looking to lose weight easily and effectively, something that doctors say would save millions of lives.

In the United States, 21 million men--26% of the male adult population--are 20% or more above their desirable weight as dictated by the Metropolitan Life Insurance Co. weight and height chart.

Twenty million American women--22.3% of adult females--are also considered overweight, according to statistician Charlotte Schoenborn of the National Center of Health Statistics outside Washington.

There is no universal definition of obesity, but health officials usually consider people obese if they are in the 85th percentile of the Metropolitan scale.

Doctors say people who are overweight tend to develop high blood pressure that puts them at risk for strokes and heart attacks. Some recent studies indicate excess body fat may also increase the risk for some types of cancer.

Overweight people also suffer from the psychological pressure of a society that equates slimness with health and beauty, doctors said.

Although scientists may debate nature vs. nurture and its application to obesity, they almost all seem to agree that humans have spent evolution preparing to gain weight quickly and efficiently.

Evolutionary Pressures

“There have been both biological and cultural pressures throughout evolution that have favored obesity,” said Peter J. Brown, associate professor of anthropology at Emory University in Georgia. “It’s resulted in a virtual epidemic of obesity today.”

Proportionately, Homo sapiens is among the fattest of all mammals, and the species’ fat is not there to insulate--as it is in whales--but to draw on as an energy reserve in times of famine.