Dr. Constantino Mendieta greeted me with ice-pick blue eyes; they did not so much pierce as impale. He had just returned to Miami, where he lives and works, from New York, where he’d undergone a small procedure. “I got my eye color changed,” he explains. Last Thursday, they were a deep brown that looked compassionate, almost dad-like, beneath his thick brows and smooth head. Post-op, he looked a bit like Mr. Clean as a plastic surgeon.

He showed me a video on his phone, which announced the search for his new eye color, voted on by his social-media audience. “Aqua Green?” “Ocean Blue” or “French Blue?” “Magical Grey” won out. The procedure, called keratopigmentation, involves a laser and some risk. “It takes a half-hour,” he says. “It took my wife longer to get her nails done!”

Miami, all white and blue, seas laced with highways, palm trees sprouting from rooftops. The route from the Atlantic Ocean to Dr. Mendieta’s office takes about 20 minutes and is lined with blanched condo towers gradually losing altitude. His clinic recently annexed another location just down the South Dixie Highway. What appeared to be a Bruno Catalano kouros stood guard in the waiting room, his carved bronze body erased from chest to knees.

Dr. Mendieta is both sculptor and sculpture. I contacted him because I wanted to write a story about male-butt augmentation, of which he is not only a giver but also a receiver—he had his butt done five years ago, “but I didn’t have a lot of fat, so mine has gone away,” he says. “Would I do it again? Hell yeah.” He’s also had five sessions of liposuction, two face-lifts, “hair transplants that didn’t work,” a nose job, and the “Magical Grey,” all of which he gleefully admits to. “Men just don’t want to be associated with any kind of cosmetic procedures,” he said. “Myself, I love it.”

In 2000, Jennifer Lopez wore a Versace dress to the Grammy Awards, creating a seismic cultural event that would spawn Google photos, and Dr. Mendieta attained board certification in plastic surgery. Lopez’s dress inspired him to start a Web site, buttsbymendieta.com, advertising gluteal implants. He soon switched to using fat culled from liposuction. “Fat became the liquid gold,” he told me. “The most dreaded part of the human body for centuries became a gold mine for me.” He’s now one of the foremost practitioners of the craft. Most of his patients are women, but his male population is growing.

The Brazilian butt lift, or B.B.L., now commonly refers to a one-two plastic-surgery punch: fat is removed from the midsection and injected into the buttocks. The invention of the B.B.L. is often credited to the Brazilian surgeon Dr. Ivo Pitanguy in 1960, though Dr. Pitanguy began with implants. The contemporary procedure’s likeliest birth date is closer to 1996, when Dr. Leonard Grossman performed a gluteal-fat graft on a Brazilian patient for the Learning Channel. Dr. Pitanguy died in 2016, the day after carrying the torch through Rio de Janeiro at the Summer Olympics opening ceremony. One obituary, remarking on his legacy in buttocks augmentation, made the unusual mention that “also credit must be given to U.S.-based surgeon Tino Mendieta.”

“You’ve got to define the buttock area from what I call the frame,” Dr. Mendieta explained to me. Masculine butts have sharp edges, while feminine ones slope. Once the frame is completed, the roof can go up, and each cheek can be molded in profile. Dr. Mendieta whips out his phone to show me an astonishing recent transformation. Before: a humble butt, the cheeks seeming inverted, as if bashful. After: they had risen, as if baked.

In the current vogue, there are two ideal male butts. One is athletic, the “Brady butt,” as Dr. Mendieta calls it, because it tends to follow football players. They have square frames and hip dips, or the indents that appear where glute muscles converge. The other is the classic “rounded, Speedo, kind of grabbable bubble butt,” describes Dr. Douglas Steinbrech, a plastic surgeon in Manhattan. Dr. Steinbrech’s practice—Alpha Male Plastic Surgery—is overwhelmingly male, and he specializes in a proprietary technique he calls BodyBanking, where fat is used to enhance musculature. “If you have a cookie or a cake, the carbs and calories end up going to fat cells,” Dr. Steinbrech explained—typically on the inner and outer thighs, or in the midsection. Dr. Steinbrech takes these “carb sink” fat cells and adds them to areas of the body where volume is more desirable, like in the peaks of shoulders or the rounds of glutes. “A year later, you can watch Netflix and have that bowl of ice cream guilt-free.”

(This pitch was so symmetrically gorgeous in its logic that I had to run it by two other plastic surgeons. “The beauty of this procedure is that since the fat is your own living tissue, it will still act like fat from the place it came from. This means that it may grow during weight gain,” said Michael Schulman, a plastic surgeon in New York. David Sieber, a plastic surgeon in San Francisco, was less convinced. “That’s just not how it works,” he said. “There have been studies looking at fat transfer to muscle groups and the fat moved there doesn’t really survive—it instead stimulates the muscle to hypertrophy.” In other words, either the fat cells become muscle, or they quickly burn off.)

The doctors I spoke to could not describe the average male B.B.L. patient—they vary in all sorts of demographics—but the most common recipients tend to be gym rats who have trouble achieving their desired geometry. (Bodybuilders, whose low fat content restricts liposuction, turn to implants for extra volume.) They want to get bigger. And they do because other men are getting bigger around them: actors on our screens are becoming Marvel-size; civilians on social media are becoming TikTok trainers and OnlyFans models, or both; pants are getting tighter and thinner; and there are wonderful things you can do with fat these days. Liposuction is the most popular plastic-surgery procedure in the U.S. A 2022 American Society of Plastic Surgeons report noted a “staggering 325,669 procedures performed” and an “impressive 23% increase since 2019.” What else can you do with all of that junk?

As Dr. Mendieta points out, beauty trends pioneered by women usually slowly come for men, and the same is true of plastic surgery. “But men are stuck back in the 80s and 90s, where it’s a taboo. They come in a lot, and they’re a little bit nervous to talk about the butt. So they start off with lipo. They get it done. And then, as they’re walking out the door, they go, ‘Hey, what about my butt?’” In 2022, men accounted for 2 percent of all American B.B.L.’s performed.

The main risk associated with the procedure is putting fat where it doesn’t belong, particularly anywhere near a blood vessel. But a misconception that the procedure is uniquely dangerous has largely been fed by tales of medical tourism gone awry and an alarming 2017 report that suggested that 1 in some 3,000 gluteal-fat transfers ended in fatal embolisms. This inspired the establishment of an international B.B.L. task force. (More recent studies show that the procedure has become much safer. When performed by a board-certified plastic surgeon, the procedure has a fatality rate closer to 1 in 14,000, about the same rate as a tummy tuck.)

The Florida Board of Medicine instituted a “subcutaneous-only” rule for fat grafts. Doctors can inject only above the muscle, and they have to use ultrasound guidance to see exactly where things are going. The future of the B.B.L. looks a lot safer than its past. Perhaps the most important things are that your B.B.L. practitioner is board-certified in plastic surgery and that they have done this hundreds, if not thousands, of times.

I spent hours on RealSelf looking at before-and-afters and reading healing diaries, knee-deep in the discharge, which is how I found Rian Maercks, M.D., another Miami-based body sculptor. On his Web site, Dr. Maercks advertises men’s Brazilian butt lifts, gluteal auto-augmentations, and lifts. It was difficult to secure an interview. I e-mailed three times, called twice, and spoke to a receptionist, and, despite my attempts, I could not seem to escape the clinic’s digital-marketing funnel. Then I tried something else—I booked a consultation. One click later, my appointment was confirmed.

The Maercks Institute occupies the two penthouse levels of a square, glass complex on Biscayne Boulevard. I undressed before the bay and its waterborne mansions. Then I waited. Dr. Maercks was, as it happened, in the middle of a B.B.L. somewhere else on the floor. A woman guided me to a room, where she took photos of my naked form on a huge machine. (Was she a nurse? I’m now wondering.) The photos were assembled into a 3D image, and my body was in their system.

Dr. Maercks is handsome, scruffy, and busy. His patient base is only slightly more female than male—60/40, he estimates, with most men going for rhinoplasties for stronger noses and blepharoplasties for smoother eyelids, and others looking for enhancements south of the neck. “Ninety percent of the time that I do bodywork on a man, I’ll be doing fat-grafting to the glutes and pecs,” he said. “I make them look like they spent the past two years in the gym.”

He pinched my right love handle and said, “This stuff is like gold.” I blushed. He took a red marker to my ass and a few moments later had sketched what looked like a topographical map of a low-lying prairie. Apparently, fat deposits on my lower back could be carved out with liposuction and injected into the rounds of my cheeks. “And then you have a little linebacker butt,” Dr. Maercks said.

“Would you call this a standard B.B.L.?,” I asked.

“I wouldn’t,” he said, “because not a lot of other people do it.”

The average cost of a B.B.L. in the U.S. is about $6,500, though in Miami, $10,000 might be a safer bare minimum. This is not a time to be thrifty—this is how embolisms can occur—but it will be interesting to see how the cost changes as the popularity surges. I also asked doctors about any new technologies on the horizon and didn’t hear much, save for one science-fiction-flavored anecdote from Dr. Steinbrech: “People are devising companies where you may use growth factors from a celebrity,” he told me, sounding a little uneasy. “I don’t want to say who.”

When I returned to the hotel, I was greeted by the clerk—his compassionate, brown eyes and also his mouth informing me that the elevator was unfortunately out of order. Apparently, a child had pushed all of the buttons at once. He apologized profusely and told me what I already knew: I would have to take the stairs.

Brennan Kilbane is a New York–based writer. He is originally from Cleveland, and his interviews and essays have appeared in GQ, New York magazine, and Allure, where he was recently on staff as a features writer