Let's be honest: News of an easy way to have a bigger penis tends to make guys' ears perk up. But the reality behind enhancing the size of your natural endowment is often messy, dangerous, and complicated.

According to British tabloid the Sun, the latest penis enhancement craze in the U.K. is a "natural" procedure by a company called Stem Protect that uses stem cells and fat from a patient's body to increase the size of their member by as much as 3 inches.

What role do the stem-cells play, exactly? Stem Protect did not immediately respond to our request for more information on the procedure, and the details in the Sun's article are a little bit fuzzy. They say the "stem cells bond with existing penis content to create [a] longer, fuller look," but they also suggest the stem cells are only there help the fat implants heal.

For help sorting out what's really going on here, we turned to a board-certified plastic surgeon in New York. Dr. Darren Smith, a surgeon at Rapaport Plastic Surgery, tells Men's Health the procedure seems to be a routine existing method of performing a penis enhancement. What's more, Smith says adding stem cells to the mix wouldn't really make much of a difference, size-wise.

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The Sun's report is mostly based off of a Stem Protect blog post, which states that "a combination of fat collected via liposuction, and healthy stem cells from a patient’s own body, can provide a new form of penis, breast and bottom augmentation that far surpasses any kind of enhancement surgery available before."

Doctors harvest fat from a patient's belly, then use a machine to isolate and concentrate stem cells in it. That stem cell-fat combination is injected into the penis to make it bigger.

This isn't a new procedure. Dr. Smith noted that we've been doing penis enhancements using fat injections for years. It's less invasive than other procedures, which sometimes peel back the outer layer of penis skin and use medical-grade cadaver skin to increase the penis's girth, but it also has the potential to come out lumpy or uneven.

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"The only thing that’s at all novel about it in this context is separating out stem cells from the fat," Smith said. "I’ve certainly heard of it in a lot of other contexts."

If the Sun's graphic is to be believed, the stem cells contribute to a "longer, fuller look" in the penis. But Smith says that's not really what stem cells would do at all. The main benefit of stem cells, and why they're used in so many other medical procedures, is that they dramatically improve the body's ability to heal. Smith said that using stem cells in the process would improve patients' skin quality — he compared the process to something called a "vampire facial," where blood platelets are used to rejuvenate skin on people's faces — but wouldn't really have an affect on their size.

"Stem cells aren't particularly useful for adding volume or length to an area," Smith said.

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The takeaway? Stem cells may help make the skin on your penis healthier, but any size increases would come from the injected fat. If you're thinking of getting an upgrade, Smith offered a few words of caution.

"Before engaging in anything like this it’s important to see if there’s any data or reputable experts behind it," he said. "And two, make sure you’re going to somebody who’s well qualified to do this."