Saturday, January 20, 2018

Next weight loss trend: Weighted vests

Our skeletons may help to keep our weight under control, according to a fascinating new study with animals.

The study [published in PNAS] suggests that bones could be much more intimately involved in tracking weight and controlling appetite than scientists realized. ...

...the scientists implanted tiny capsules into each rodent’s abdomen. Some contained weights equaling about 15 percent of each animal’s body mass. Others were empty. ...

The scientists then left the rodents alone to deal with these added ounces as they would. And their bodies quickly went to work. Within two days, the animals containing the weighted capsules were eating less and after two weeks, had generally lost almost as much weight as the capsules contained.

When the scientists subsequently removed the weighted capsules from some of the animals, those mice and rats began eating more and soon added back those ounces. ...

Finally, the scientists considered bones. As they knew, most animals’ skeletons readily sense when they are being stressed by such things as strenuous weight-bearing exercise and will add extra bone cells to handle that pressure.

Osteocyctes, a type of bone cell, are thought to be the cells that recognize when outside forces are affecting the bone and send out biochemical signals prompting the creation of new bone.

To see if they likewise detect and respond to changes in body weight, the scientists bred a group of mice with unnaturally low levels of osteocytes. Then they again implanted the weighted capsules.

This time, the animals did not drop that added weight. Their bodies did not seem to realize that they had become heavier, presumably because of the low levels of osteocytes, and the animals remained artificially plump.

The implication of this result is that healthy bones seem to sense changes in body mass and then somehow initiate alterations to appetite and eating that can return the body to its previous weight, says John-Olov Jansson, a neuroscientist at the University of Gothenburg who led the study. ...

The possibility could help to explain why sitting for hours is associated with obesity, he continues. When we sit, much of our body weight is supported by cushions rather than bones, leaving our skeletons unaware of how much we actually weigh and whether that amount has changed or should change.
--Gretchen Reynolds, NYT, on the thigh bone being connected to the potbelly bone