Your bones may know when you’re getting fat

I often harp about the fact that your body wants to stay the same weight. You lose weight; you gain it back. Just look around you. People look about the same year after year. It’s called homeostasis—physiological stability. Lots of mechanisms are at play here. For example, our fat cells release the hormone leptin into our bloodstreams. It tells our brains we've had enough to eat. Conversely, when leptin levels drop, our appetites return--it's a system to keep us from starving. Now, some scientists think they may have discovered another source of weight stability: our bones.

To see if added weight triggered weight loss, scientists implanted tiny capsules into mice abdomens. Some of the capsules contained weights and some were empty. Within two days, the animals that harbored the weighted capsules were eating less, and, after two weeks, had lost almost as much weight as the capsules contained. After removing the weighted capsules, the mice started eating more and regained the lost weight. The scientists repeated the experiments with mice that had been bred to produce very little leptin, yet the results were the same.

In trying to determine what caused this phenomenon, the scientists started looking at bones, which can sense the stress of added weight (including weight-bearing exercise). To handle that extra pressure, bones start adding new bone cells, a process that's triggered by cells called osteocytes. Now it looks like those osteocytes may also be sensing changes in body mass and, in response, sending biochemical messages that affect changes to appetite. To test this, the scientists bred mice with unnaturally low levels of osteocytes and implanted the weight capsules into this group. This time, the animals did not drop the added weight. Apparently, without osteocytes, their bodies did not realize they’d become heavier.

Okay. So what this says to me is that we could strap on some weights to trick our bones into thinking we’d become heavier. Our osteocytes would leap into action and curb our appetites. You first.

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