NEW ORLEANS (AP) â€” A thrifty gene that helped cavemen survive food shortages appears to be a common underlying trigger of both obesity and diabetes, researchers reported Monday.
German researchers said the gene apparently prompts the body to store up fat for later.
They said the gene could be an important explanation of an inherited tendency to gain weight, especially among black people. Their work shows that about 90 percent of blacks, 50 percent of Asians and 30 percent of whites carry at least one copy of this gene.
``This gene was advantageous in times of food scarcity,'' said Dr. Achim Gutersohn. ``But in times of driving and coach potato-ing, it can cause obesity.''
The links between genes, living habits and health are of increasing interest to researchers, and this association appears to be especially complex in the way people gain weight. Experts believe that perhaps 30 or 40 genes can increase the tendency to obesity. But these genes operate in concert with each other as well as with people's exercise and dietary habits.
``This is a hint of where medicine is going â€” gene and environment interactions,'' said Dr. Robert H. Eckel of the University of Colorado Health Sciences Center.
He said doctors may someday routinely look for genes that increase the risk of obesity, and drugs may be developed to target specific genetic profiles.
Still, he said, people's eating and exercise habits are probably much more important than their genes in determining whether they are overweight.
In fact, the German researchers found that exercise can counteract the bad effects of the gene studied. People who exercise just two hours a week appear to escape the gene's tendency to add weight.
Everyone inherits two copies of every gene at birth. The German group focused on one that manufactures G proteins, substances that carry messages from the surface of cells into their centers. One normal variety of this gene is called the GNB3 825T allele.
The researchers found that people who inherit two copies of this particular gene type are three times more likely to be obese than are those who get one copy or two completely different variations of the gene.
The gene seems to be especially important after childbirth, when women need to lose the weight they put on during pregnancy. Those with two copies of the gene were six times more likely than usual to keep their extra pounds â€” but only if they did not exercise.
Worldwide, the researchers found that about 60 percent of black people carry two copies of the gene, compared with 20 percent of Asians and 10 percent of whites.
In work on young Germans, the group found that 8 percent of those who were of normal weight carried two copies of the gene, compared with 23 percent of people who were obese.