Researchers might have found an explanation for why sitting is tied to weight gain and poor health. A new study on mice led to the hypothesis that it has to do with gravity sensors in the bones of our legs, called osteocytes, which act as a bodyweight scale.

Osteocytes are a type of cell that sense outside force on bone and adapt accordingly, explains study author Jan-Åke Gustafsson, MD, Ph.D., founding director of the Center for Nuclear Receptors and Cell Signaling at the University of Houston. These cells help regulate bone mass but the study results suggest they also do so for fat mass—at least in mice, he says.

Since sitting removes the force of our body weight from our bones, osteocytes in our legs mistakenly think we weigh less and try to get us back to homeostasis by sending signals that increase our appetite, Gustafsson explains.

Gustaffsson and his team still need to test the theory in humans, but the discovery in mice is an exciting prospect that could help explain how our body regulates weight gain. Until then, move more throughout the day to remind your bones what your natural weight feels like.