NEW YORK (Reuters Health) - When it comes to resisting the siren call of sweets and other goodies, genes may make all the difference, researchers say.

The answer to whether you can eat just one chip, or say no to that luscious piece of chocolate cake, may be locked deep in your DNA, according to a study published in the American Journal of Clinical Nutrition.

"Although environmental, psychological and physiologic factors affect appetite and nutrient intake, several studies suggest that behaviors such as food and beverage preferences and nutrient intake are at least partially genetically determined," report Dr. Alan Shuldiner, of the division of endocrinology, diabetes and nutrition at the University of Maryland School of Medicine in Baltimore, and colleagues.

Shuldiner's team wanted to take a closer look at the genetics of obesity and the eating behaviors that lead to it. To do this they studied the eating habits and genetics of 624 adults from 28 Pennsylvania Amish families who participate in the Amish Family Diabetes Study, which was started in 1995.

The Amish families "are wonderful for genetic studies," Shuldiner said in an interview with Reuters Health. "They are all descended from a homogenous founder population. They all reside in a relatively localized area. And they keep extensive geneologic records."

All study participants were asked to fill out an eating habits questionnaire that included true or false queries, such as: "I do not eat some foods because they make me fat"; "When I am with someone who overeats, I usually overeat too"; and "I get so hungry my stomach often feels like a bottomless pit."

The researchers were looking at three major eating behaviors. One is restraint, a measure of whether a person can say no if he thinks another goody might make him fat. Another is disinhibition, which is a measure of whether people have a hard time saying no to a second helping of a favorite food. The third is hunger.

Shuldiner and his colleagues also checked fasting blood sugar, cholesterol and body mass index (BMI) for each study participant. BMI is a measurement of weight in relation to height.

The researchers found that restraint, disinhibition and hunger scores correlated with obesity and that high scores tended to run in certain families.

The investigators next decided to search the genome of the families with high scores to see if they had bits of DNA in common. The researchers isolated regions on certain chromosomes that seemed to be linked to restraint and disinhibition.

While they haven't yet found the exact genes that are linked with each eating behavior, there are candidates--found by other researchers--that reside on the chromosomes of interest.

For example, Shuldiner's group found that a region of chromosome 3 appeared to be linked to a person's ability to pass up second helpings of food. Located in this section of the chromosome is a gene that encodes a receptor that is found in large quantities in fatty tissue.

Shuldiner hopes that the genetic research will ultimately help scientists find better treatments for obesity. "Insights gained by identifying genes that influence eating behavior may provide new molecular targets for the early detection of individuals susceptible to obesity, which may advance the development of preventive interventions and provide new drug targets for the treatment of obesity and related disorders," he and his colleagues write.

SOURCE: American Journal of Clinical Nutrition 2002;75:1098-1106.

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