MONDAY, Aug. 14, 2006 (HealthDay News) -- Different brain biology may explain why some people tend to be couch potatoes while others are more active.
That's the conclusion of a U.S. study that found some brains may naturally encourage restless behaviors that burn calories and help control weight.
Researchers found that the brains of rats bred to be lean are more sensitive to a chemical produced in the brain called orexin A. This chemical stimulates appetite and spontaneous movement such as fidgeting and other minor unconscious movements.
The study also found that the lean rats had a far greater expression of orexin receptors in an area of the brain called the hypothalamus, compared to rats bred to be obese.
"The greater expression of orexin receptors suggests the lean rats' brains were more sensitive to the orexin the brain produces. The results point to a biological basis for being a couch potato," senior researcher Catherine M. Kotz, of the VA Medical Center, University of Minnesota, and the Minnesota Obesity Center, said in a prepared statement.
She said this line of research suggests that frequent unconscious movement, such as fidgeting, may burn calories and help control weight. It also suggests a possible new way to control weight and could lead to the development of drugs to stimulate minor physical activity.
The study was published in the online edition of the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology.
The U.S. National Heart, Lung, and Blood Institute has more about physical activity.