The Federal Trade Commission (FTC) issued an Enforcement Order this week: two brands must stop claiming caffeinated underwear will make your behind smoother and slimmer. What did they do to get the FTC's knickers in such a twist?

*"The FTC's complaint ... alleges the company deceptively advertised, marketed, and sold women’s undergarments infused with micro-encapsulated caffeine, retinol, and other ingredients... *the company made claims that wearing its shapewear would eliminate or substantially reduce cellulite; reduce the wearer’s hip measurements by up to two inches and their thigh measurements by one inch; and reduce thigh and hip measurements “without any effort.”

It's pretty understandable why some women would have wanted that to be true, but once again science and chemistry get in the way of a great fairy tale.

Reaping What They Have Sewn

The product label tags describe just what got into your iPants: (via FTC)

*"The revolutionary new anti-cellulite iPant from Wacoal. ...*embedded microcapsules combine the best selection of active ingredients: caffeine, retinol, ceramides, vitamin E, fatty acids and aloe vera. Caffeine is a renowned active slimming agent that promotes fat destruction."

The Norm Thompson online catalog has already been expunged of all claims of weight loss, but from the FTC documents:

*Take up to 2” off hips and 1” off thighs in just weeks. The shapewear’s secret? Caffeine. . . . *Caffeine helps break down fat; botanicals flush out toxins.

The label on a pair of iPants. Note the instructions to wear the pants 8 hours a day, 7 days a week, for 28 days. FTC/Wacoal

The instructions on both versions of the pants are to "wear 8 hours a day, 7 days a week, for 28 days" for best results. Anyone who has struggled into a pair of Spanx™ knows that shapewear is hot, uncomfortable, and not fun.

Wearing tight, damp, sweaty underpants that include micro-encapsulated lotion day after day... this is not appealing. "Hope on a Hanger" sounds more like "Yeast Infection in your iPants."

The FTC also ruled that the trials relied upon to make these claims were faulty: they were unblinded, had no controls, and even then didn't produce the results claimed. After 28 days of wearing caffeinated britches, the average hip circumference reduction was less than 0.166 of an inch; the average reported thigh reduction was 0.125 of an inch.

Seat of Contention

Just how far-fetched is the claim that you can caffeinate your ass? Can you actually absorb caffeine through your skin? I made a quick call to my go-to person for all things chemical, Dr. Raychelle Burks of Doane College. Her take on the pants was similar to mine:

"There is so much wrong with this. You can't just wear magic pants."

Caffeine is both water and fat soluble; that's how it gets into your skin. That also means that when you wash it, lots of the caffeine will be washed out of the fabric. Burks said "when I buy new anything—bathing suit, jeans, whatever—the first thing I do is wash it before I wear it. If you wash it, the caffeine and other ingredients are soluble, and of course with soap — well, that’s the whole point of adding soap. It contains surfactants to remove all sorts of stuff."

The manufacturer's claim that "active ingredients are still present after 100 washes" seems unlikely. The initial concentration of caffeine and vitamins would have to be extremely high; or the ingredients are treated to be so non-soluble that they then probably don't absorb into the skin.

But would it actually have any effect? The ability of caffeine to dissolve across skin is well documented, but what it does after that is a bit unclear. Burks suggests that the caffeine won't just stay put; even assuming it makes it past the many layers of skin to the fat that you want to target, a great deal of the caffeine will be taken up by cells on the way.

As for the claims about cellulite, Burks provided one of the best explanations I've ever heard for why those cottage cheese thighs are so hard to get rid of: "It's an engineering issue." Cellulite results from the interaction of connective tissue, fat deposits, and muscles. You can't sweat it away, or caffeinate it away. It's just how human animals are built.

The Bottom Line

After a public comment period, Norm Thompson Outfitters and Wacoal America will pay pay $230,000 and $1.3 million, respectively. This seems a pittance, given some underpants sold for up to $80 apiece.

A variety of other manufacturers and retail outlets offer versions of "cosmetotextiles," or clothing impregnated with cosmetic and drug ingredients. Researching this story was a trip down a very freaky, body-shaming rabbit hole.

From a product description: "For the Corrective belt, the active ingredients are Caffeine and Shea butter; for the Panty Push Up, Caffeine and Mango butter." I found caffeinated yoga pants with the remarkable name of "Hu-Nu Woo-Hoo pant." For the toning of one's Hoo-Ha, I guess.

It's unlikely that the FTC will be able to track down all sources of these garments, so caveat emptor applies. Don't give people making outrageous claims your money. "Any claim that a product worn on the body causes substantial weight loss is always false."