Gene to Body: Store Up Fat ; Cu Doctor Says Dna Might Explain Why Dieting May Not Work

You see them everywhere – slim-hipped, lean-legged, skinny people, defying the trend in fat-and-getting-fatter America.

Do they eat less and exercise more to keep those svelte limbs?

Well, maybe, say endocrinologists who specialize in obesity research.

But it’s just as likely that these people are willowy because several generations back, their ancestors lost the so-called thrifty gene.

Hundreds of endocrinologists will gather in New Orleans this week to talk about obesity and how an understanding of glands and genomes can help loosen its grip on adult Americans.

Endocrinology is the study of the body’s hormone-producing glands and the functions of the hormones they synthesize and secrete.

Endocrine Society President Dr. Chester Ridgway, of the University of Colorado, chose obesity as the theme of ENDO 2004 because “obesity is such a pressing health problem and imminently linked to endocrinology.”

Ridgway, head of endocrinology at the CU School of Medicine, doesn’t believe that whether a person is fat or slim has only to do with diet and exercise.

It may have to do with the thrifty gene – or, perhaps, thrifty genes- those handy codes inside the DNA that harken back to the times when starvation was a real threat to humans everywhere. These genes instruct the body to store fat whenever there is a surplus.

“Our predecessors were very nomadic and had to really eat what they killed or found,” Ridgway said. “When food sources were scarce, starvation was a real problem. There was a genetic selection for those who could store calories the best.”

Then came cities, the industrial revolution and the TV remote control in close proximity to the refrigerator.

For much of the population, “our genes didn’t change, but things started changing around us – the automobile, packed-caloric food.”

People living in fast-food nation, who still have that gene that protects them from starvation, can be in real trouble, Ridgway said. Each burger or cookie gets stored as fat.

Thousands of years after humans stopped their nomadic ways, many people lost that gene. But many have retained it, making weight loss a tougher battle.

All of which isn’t an argument for giving up and sitting on the couch, Ridgway said. Burning more calories than you’re eating is still the only way to lose weight.

Indeed, 90 percent of Type II diabetes would disappear if the people with that disease got down to their ideal body weight, he said.

Among the hot research topics being pursued by endocrinologists at CU and elsewhere are:

* Findings that obesity in men makes it harder to father children.

* Mapping the brain to find out what lights up when someone is taking in food. This will make it easier to develop treatments for overeating.

* Finding an effective appetite suppressant. Rimonabant is an intriguing candidate, and so is the hormone PYY.

PYY is in the gastrointestinal tract but travels to the brain to decrease appetite. Many obese people apparently have very little of this protein.

“If we can find out the structure of this protein and make a compound to mimic PYY, we could use it as a drug to suppress appetite,” Ridgway said. “Everyone is watching this closely.”

In the meantime, it may be time for the lean to have some sympathy for the plump and reflect that obesity may have a lot to do with ancestors long departed.

INFOBOX

How does the ‘thrifty’ gene work?

* In certain nomadic populations, hormones were released during seasons when food supplies were traditionally low, which resulted in resistance to insulin and efficiently increased fat storage.

* The process was reversed in seasons when food was readily available.

* Because modern industrialization has made high-carbohydrate and fatty foods available all year long, the gene no longer serves a useful function and is now harmful because fat is not used up.

Source: Preventdisease.Com