NBA basketball player Charles Barkley was nicknamed "The Round Mound of Rebound" during his playing days because of his ability to snag rebounds despite his well-padded physique. In his 16-year career, he snagged more than 10,000 rebounds and 20,000 points, while dishing out some 4,000 assists.

Barkley is lucky that he was so active while he was (and still is, sometimes) carrying around extra padding. It turns out that lifelong exercise offers powerful compensation for the inevitable decrease in your fat cells' ability to help you maintain a healthy metabolism.

Surprise: Fat cells aren’t all bad.

Body fat (not around the belly, but in moderation all over your body) is not just passive; it's an active organ that interacts with other organs. And its cells’ tiny power plants, called mitochondria, provide energy so you can run, jump, dunk, and fight off destructive inflammation.

A Danish study published in the Journal of Gerontology compared fat cells’ mitochondrial performance in young and older untrained, moderately trained, and highly trained guys' cells.

It showed that although even highly trained older men's mitochondria were less able to produce energy than younger men's, they were still able to produce more than twice as much as the mitochondria in untrained older men's cells.

Even if you're slowing down, make sure you get a regular schedule of physical activity. You want to stoke the fires that keep all cells — including fat cells — healthy by walking 10,000 steps a day, strength training, and moving, moving, moving.