Depending on who you talk to, Spanx are either the greatest invention ever — or weird and uncomfortable. I fall into the former category. While I don't wear them very often (at most once a month or so), they are an amazing thing when I do, creating a line-free (and slimmer) silhouette under dressier clothing. For those who don't know, Spanx are basically just compression undergarments that use the power of elastic to flatten and smooth baggy, cellulite-covered or otherwise imperfect skin — I think of it as "real-life Photoshopping." Everyone from celebrities to the working-woman-next-door have jumped on the Spanx bandwagon, making the company's founder and CEO a multi-millionaire. 

I work out almost every day, and am conscious about what I eat, but ever since I was a kid, I've always had a little belly, and as I age, it's not going anywhere — at this point I'm just working on ensuring it doesn't expand. Spanx helps keep what I'm most conscious about out of the spotlight if I'm wearing something form-fitting; and because many people have different areas that they would like a bit of camouflage for, there are various types of Spanx — for the back to hide rolls of fat there, for the butt, and for the entire leg. And yes, there are even Spanx for men. 

But — and is this really a surprise? — wearing Spanx on the regular probably isn't good for your health, especially if you are wearing the tummy-control Spanx (which are the company's most popular and the original product). Because it's tight, it compresses organs —  including stomach, intestines, colon, and bladder — gastroenterologist John Kummerle told the Huffington Post. "In someone who has weakness down below and a tendency towards incontinence, increasing intra-abdominal pressure can certainly provoke episodes of incontinence," says Kummerle. Shapewear doesn't let food get digested as it should, and slows down the entire process, especially if it is too tight. 

Even for people without already existing digestive issues, wearing restrictive shapewear (and yes, there are other companies that make these items beyond Spanx), can bring on episodes of acid reflux or heartburn. Ironically, this slower, restricted digestion can lead to bloating (just what shapewear purports to fight!) and gas. Other potential issues include shortness of breath and tingling or numbness in the legs if the Spanx are cutting into your upper thighs when you sit. (And the same thing can happen with too-tight tights or pants, by the way.)

But there is a way to do Spanx and shapewear right (thankfully for all us fans out there). First, get the right size. Shapewear should hold you in and smooth your curves, but not restrict. Be sure you can move and breathe comfortably (I can breathe fine in my Spanx; I was on the line between two sizes and went up, not down); you should also be able to bend and sit without it cutting into your body at any point, especially at your waist and the tops of your thighs when you sit. And it's probably best not to wear them all day, every day. 

It's really OK to wear comfortable clothing sometimes too; it doesn't mean you're lazy or sloppy (try a flowy silk blouse over a maxi skirt, belted at the waist; this look is on-trend right now and quite comfortable too — loose, full-legged pants are also back in style for 2014). 

Related on MNN: 

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.

Spanx could be harmful to your health
The incredibly popular shapewear could cause digestion and circulation issues.