Does being overweight affect your activity potential? You’re darn right it does. If you’d rather sit on the couch than haul your butt to the gym or go for a jog, new research suggests the extra weight you’ve been carrying around may be the reason. It may seem obvious.
A new study suggests that diet-induced obesity alters the brain’s functioning in ways that suppress the natural impulse to move around. It occurs because the obese may have compromised dopamine receptors, resulting in a lack of motivation for exercise.
Many factors determine our motivation to exercise — including proper facilities, leisure time and the social encouragement to do so. But new research with mice confirms that obesity disrupts the proper functioning dopamine, a brain chemical that affects our moods, appetites, and motor control.
Consequently, the chubbier the mice the more likely they are to become couch potatoes.
When researchers from the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) fed the mice either a standard or a high-fat diet for 18 weeks, by week two, the mice on the unhealthy diet were visibly heavier and by the fourth week, the fattened rodents spent less time moving and were a lot slower than their counterparts when they did.
Researchers also noticed the activity of a specific class of dopamine receptor known as D2 in the brain’s striatum (a center of movement control and reward-seeking behavior) begin to fall.
“There are probably other factors involved as well, but the deficit in D2 is sufficient to explain the lack of activity,” said Danielle Friend, a postdoctoral fellow at NIDDK. “We know that physical activity is linked to overall good health, but not much is known about why people or animals with obesity are less active,” said Alexxai V Kravitz from NIDDK.
“There is a common belief that obese animals do not move as much because carrying extra body weight is physically disabling. But our findings suggest that assumption does not explain the whole story,” said Kravitz
To prove the point, researchers turned off the brain receptor’s activity in lean mice, fed healthier food and they too lost their impulse to exercise… however, they did not gain weight and become obese. Not unexpected, when researchers took obese mice and experimentally “turned up” the receptor’s faulty signaling, they saw the chubby mice step up the frequency of their physical activity.
About 30% of Americans do not engage in any regular physical activity. Worse, 8 in 10 American adults don’t meet government recommendations for activities that build aerobic fitness and strength.
