Overweight mice may provide a link for people struggling to exercise consistently. Researchers from the U.S. National Institute of Diabetes and Digestive and Kidney Diseases found data in a study they conducted from mice brains that may encourage inactivity. While physical activity is linked to good health, there is not much known about the links between obesity and activity. The brain chemical dopamine may be a key to the inactivity and obesity in mice.
Obesity is a frequent and severe medical condition where excess fat has gathered to the point that it can negatively affect a person’s health. Caused by a combination of a lack of physical activity, excessive eating habits, and a genetic disposition, some cases of obesity can be caused by endocrine disorders, medications or even mental illness. Obesity can be prevented through improved diet and exercise. In the U.S., obesity is now a major health concern with obesity rates as among the highest in the world. Two out of every three Americans are considered to be obese. Obesity can lead to conditions such as heart disease, type-II diabetes, and certain types of cancer.
Dopamine is an organic chemical that plays many important roles in the brain and body. In the brain, dopamine functions as a neurotransmitter that sends signals to other nerve cells including a distinct pathway that is major in reward-motivated behavior. Rewards increase the level of dopamine in the brain, and many addictive drugs increase neuronal activity. In other parts of the body, dopamine acts as a local chemical messenger.
The study, published in the journal Cell Metabolism found that obese mice had fewer receptors to process dopamine than mice that were not obese. Alexxai Kravitz, Ph.D., corresponding author, and investigator with the Eating and Addiction Section, Diabetes, Endocrinology, and Obesity Branch of the NIH, said that while overall good health is linked to exercise, there is not much known about why obese people are less active, Tucson.com reported. His study disproved the theory that obese animals do not move much because of their extra weight but instead expend more energy because of it.
While many studies looked at the reward processing of eating food connected to obesity, this study looked at dopamine signals in the brain. The study fed standard and high-fat diets to mice. The mice on high-fat diets naturally put on weight and slowed down but, the researchers noted that the mice slowed down before the weight increased. Researchers wanted to know why these events happened in this order. One theory was obese mice had fewer receptors to process the dopamine.
Health reported Kravitz as saying willpower is a way to modify behavior. However, if the underlying physical basis for that behavior is not understood, then it cannot be determined whether willpower alone can solve it. Understanding the physiological reasons why obesity and less activity are linked may also reduce some of the stigmas faced by obese people. More research about the link between dopamine and exercise struggle in obese people is needed before proving the theory.
By Cheryl Werber
Photo Courtesy NBC