This Might Explain Why Some of Us Are Couch Potatoes
By LIDA TUNESI
Conversations about weight and obesity commonly revolve around diet and levels of consumption, but that’s not the whole picture. Physical activity is important, too.
Now a new study is shedding some light on why some of us are motivated to exercise, while others find it hard to get off the sofa and hit the gym.
“The work in this paper, though an incremental step, might help us understand the ‘couch potato’ syndrome,” Professor Jeff Beeler (The Graduate Center, Queens College). “This may be important not just for obesity, but for many neuropsychiatric conditions associated with loss of energy, such as depression.”
A recent study from Beeler’s lab, published in Neuroscience, offers new insight on the subject, suggesting that dopamine D2 receptors (D2R) in the brain are important for regulating our willingness to expend energy. Ph.D. student Devry Mourra and master’s students Federico Gnazzo and Steve Cobos were also authors on the study.
Scientists have been debating the role of these receptors in weight for some time. Previous studies have argued that reduced signaling from D2Rs promotes compulsive eating, which drives weight gain.
The new study, while not completely negating this idea, suggests that the receptors are likely more important for regulating motivation for activity. This could explain why some people have a harder time maintaining a fitness regimen. For instance, Beeler said, people with obesity tend to have lower activity levels, even after they’ve lost weight.
The researchers used pharmaceutical and genetic methods to alter D2R signaling in mice. They then observed how much effort the mice put into a task that rewarded them with food, and how efficient their efforts were. With reduced D2R signaling, the mice made less of an effort. In other words, they were more likely to conserve their energy.
“The way that expenditure of energy is regulated is much less studied and much less understood,” Beeler said.