A study conducted on mice indicates that excess body weight is not responsible for obese individuals' inactivity, but it could be due to alteration in the dopamine receptors.

Biological Causes For Inactivity In Obese People

Often, obese people who are low on activity are motivated to begin exercise plans to improve their health. But it is hard for some people to stick to a workout program. Inducing willpower may not work for such people as there may be a biological reason behind the continual urge for physical inactivity in them.

Knowing the biological causes of physical inactivity may help in effective intrusions for increasing activity, which could assist in improving health of individuals with obesity.

Excess Weight May Not Be The Sole Reason For Inactivity In Obese Individuals

Obese people have low motivation to move, but it may not be due to the difficulty they experience in carrying their excess body weight. According to a recent study, alteration in dopamine receptors could be the reason behind the lack of activity in overweight people. Obesity may cause alteration of dopamine receptors, which in turn may affect the activity levels of the obese individuals.

Impairment Of Dopamine System May Cause Inactivity In Obese Individuals

Alexxai V. Kravitz, the study's senior author, and colleagues performed their study on lean and obese mice. In the research, the mice were fed with one of the two diets, standard or high fat diet, for a period of 18 weeks. The researchers observed that by the commencement of second week, the mice given unhealthy diet had gained more body weight. By the beginning of fourth week, these obese mice had reduced their physical movement and even if they moved, they did at a very slow pace.

Notably, the mice on high fat diet showed fewer movements even before they gained the major portion of their weight, clearly indicating that excess weight was not the only factor responsible for reduction in their movements.

The researchers examined six diverse constituents in the dopamine signaling pathway. They inferred that the inactive and obese mouse had shortage in the D2 dopamine receptor. Hence, the lack of physical activity in obese mice resulted because of the disturbance in dopamine receptors opposed to physical difficulty faced by them in carrying the excess body weight.

"There are probably other factors involved as well, but the deficit in D2 is sufficient to explain the lack of activity," said first author, Danielle Friend, in a press release.

The research is published in the journal Cell Metabolism.