I've got a belly button issue. I used to have an "inny," now I have an "outy." My gut has gone from flabby to hard like a melon. What gives? —Navel Cadet

As you grow older, your belly button gradually backs further and further out of your body, like a screw. Eventually, when it unscrews completely, your ass will fall off. This is why old people have such flat butts. You're welcome.

But seriously: I'm sorry, Cadet. I know you're hoping I'll say the transformation of your gut from a flabby quagmire into a taut pumpkin means that you're finally getting into shape, but you're not.

Before I explain, however, let's both take a moment to thank the Portland weather gods for the return of Bulky Sweater Season. This is the time of year when folks like you and me undulate out of our caves, our curves obscured by sweaters, dusters, caftans and the occasional tarp, and reclaim the streets from the lean, bronzed Summer People—who, having the thermal mass of a french fry, are forced to layer up till they're almost amorphously shapeless as us.

For the next six months, these fixie-toned unfortunates will grouse about the cold while the rest of us watch with bemused pity, like belugas observing an ice-bound grebe.

But back to your condition: Unless you're pregnant, you're probably hosed.

The depth of your belly button, obviously, corresponds to the thickness of the belly fat that covers your abdominal wall. If that layer is getting thinner while your overall weight stays the same, congratulations: You have visceral fat.

Yes, visceral fat means that instead of being carried in a layer on the outside of your body, much of your fat is now affixed to your actual internal organs. Some people have fat asses. You have fat kidneys!

Visceral fat is even more linked to heart disease and diabetes than the regular stuff. It is, however, supposed to be easier to aerobicize away. For more details, ask a real doctor.