How many injections are you willing to endure to preserve the structural integrity of your face and derrière? For a certain segment of the 1 percent, there’s no such thing as too many pricks.

After giving birth to her first child at 41, Jennifer Berger struggled to lose the last 20 pounds of the 50 she gained during her high-risk pregnancy. “I was doing a mix of cardio and weights three to five times a week, tracking everything I ate, and I still couldn’t lose that last bit of baby weight,” said Ms. Berger, a fashion merchandiser in New York.

At her wits’ end, Ms. Berger visited a doctor who suggested she try tirzepatide, marketed under the brand name Mounjaro, a buzzy new diabetes drug approved by the Food and Drug Administration in May 2022. Mounjaro regulates blood sugar, suppresses appetite and, if one is to believe the hushed accounts recently exchanged at an Upper East Side hair salon, makes excess pounds disappear into thin air.

“Everybody is either on it or asking how to get on it,” said Dr. Paul Jarrod Frank, a dermatologist in New York. “We haven’t seen a prescription drug with this much cocktail and dinner chatter since Viagra came to the market.”

The once-a-week injection works in a similar way to semaglutide treatments like Wegovy and Ozempic, the drug rumored, without evidence, to have helped Kim Kardashian fit into the tiny Marilyn Monroe gown she wore to the Met gala; Ms. Kardashian has denied those rumors. In recent months, these drugs have been prescribed so frequently off-label that shortages prevented some diabetics and obese people from getting their medicine.

Many doctors worry that the drugs’ current popularity, fueled in part by social media, has resulted in people taking them without sufficient medical supervision — a risky move considering the possibility of rare but serious side effects like thyroid cancer, pancreatitis and kidney failure. And drugs like Ozempic can also cause less serious but still debilitating symptoms including nausea, vomiting and racing heart beat, as many videos on TikTok attest (see: #ozempic).

Some of the side effects are “extremely rare if the medication is being prescribed at the right dose and with careful medical supervision,” said Dr. Rocio Salas-Whalen, an endocrinologist in New York, who said she has prescribed this family of medication and its predecessors to more than 8,000 patients since 2005.

“Mounjaro is like the Apple 14 of these drugs,” said Dr. Salas-Whalen, who did not treat Ms. Berger. Dr. Salas-Whalen said it has the same ability to control blood sugar as Wegovy and Ozempic, but that in her practice, she had seen “almost double the weight loss and close to none of the side effects.”

The F.D.A. reported that in its clinical trials, which were done on diabetics, patients taking Mounjaro lost, on average, 12 pounds more than those taking drugs like Ozempic. Dr. Salas-Whalen, who has done work for Novo Nordisk, the maker of Wegovy and Ozempic, said she has seen similar results in non-diabetic patients.

While Mounjaro may sound like the closest thing to a weight loss magic bullet since gastric bypass surgery was first performed in 1954, it is not without risk. The Mounjaro packaging contains a black box warning about thyroid C-cell tumors. Like the first generation of these drugs, Mounjaro increased the risk of a rare type of thyroid cancer called medullary thyroid carcinoma when it was tested on rodents.

None of these drugs come cheap: Unless a patient is obese and has at least one other “weight-related condition” (such as high cholesterol, hypertension, diabetes), insurance usually won’t cover the medications, which can cost upward of $1,000 for a month’s supply. (Mounjaro is $975 per month; Ozempic, $892; Wegovy, $1,350.)

The Rise of Ozempic Face

Ms. Berger, who had undergone fertility treatments to get pregnant, said she didn’t think twice about sticking a needle in her abdomen once a week — or shelling out nearly $1,000 a month for the drug. And Mounjaro lived up to its expectations. Within three months, she had lost those last stubborn 20 pounds.

“It was like flipping a switch,” she said. “I would look at food and it wasn’t even appealing, and I am someone who loves food! I almost had to remind myself to eat. It just took away all the cravings.”

Ms. Berger was thrilled with her new body. There was, however, a major downside to losing the weight so quickly. Her face suddenly looked gaunt.

“I remember looking in the mirror, and it was almost like I didn’t even recognize myself,” she said. “My body looked great, but my face looked exhausted and old.”

Dr. Oren Tepper, a plastic surgeon in New York, said that it’s common for weight loss to deflate key areas of the face, leading to a more aged appearance. “When it comes to facial aging, fat is typically more friend than foe,” he said. “Weight loss may turn back your biological age, but it tends to turn your facial clock forward.”

Indeed, as Catherine Deneuve is purported to have said: “At a certain age, you have to choose between your face and your ass.” But these days, in certain moneyed circles, that adage no longer seems to apply, with the now common combination of weight-loss drugs and volume-restoring filler.

“I see it every day in my office,” said Dr. Frank, who said he coined the term “Ozempic face” to describe the condition. “A 50-year-old patient will come in, and suddenly, she’s super-skinny and needs filler, which she never needed before. I look at her and say, ‘How long have you been on Ozempic?’ And I’m right 100 percent of the time. It’s the drug of choice these days for the 1 percent.”

Dr. Dhaval Bhanusali, a dermatologist in New York whose famous patients include Martha Stewart, has observed the same trend in his office. “We are seeing more and more patients on the medications coming in,” he said. “Generally, it’s people in their 40s and 50s who are losing significant amounts of weight and are concerned about facial aging and sagging that occurs as a result.”

While noninvasive procedures like Fraxel can improve skin texture and wrinkles, Dr. Frank said that fillers are the only noninvasive way to restore volume (cost: $5,000 to $10,000). To bring back a youthful fullness to Ms. Berger’s face, Dr. Frank injected Radiesse and hyaluronic acid-based fillers in strategic places all over her face — around the temples, under the eyes, in the buccal hollows and around the jawline, the mouth and lips.

To restore volume, Dr. Bhanusali uses Radiesse in combination with Sculptra, an injectable that stimulates collagen production and can last for up to 24 months. (Dr. Bhanusali has been a consultant to Galderma, the maker of Sculptra.) “The idea is to balance the face to offset the hollowing and downward projections at the cheeks, jowls and other areas,” he said.

‘A high-end luxury drug.’

Some people suffering from facial wasting caused by rapid weight loss — 40 to 50 pounds, say — may require a more radical approach. “When there is this much weight loss, plastic surgery is sometimes the only way to restore the volume loss,” Dr. Tepper said, noting that more than half of the patients he sees for weight-loss-related surgery are taking these drugs.

“The success rates are astonishing,” he said of the drug treatments. “For many patients, it’s like suddenly winning a lottery Mega Millions. But then they realize there’s a tax that comes with it — the loss of fat in the face — so it may not be quite the windfall they imagined.”

Dr. Tepper said he can eliminate any vestige of “Ozempic face” with a deep plane face-lift, which costs $75,000. He typically combines this with a procedure in which fat is transferred from other parts of the body to the face (an additional $8,000 to $12,000).

While the jaw-dropping prices of these treatments are clearly beyond the reach of the average person, for patients like Ms. Berger, who stopped taking Mounjaro after she returned to her pre-baby weight, feeling healthy and confident again is worth every penny she spent.

“I can’t tell you how good I feel about myself now,” she said. “I used to hide from my husband when I came out of the shower. I would literally walk backward so he wouldn’t see my backside. Now I don’t care. Because I feel good. I feel like myself again.”

Some doctors say that most patients who are taking these drugs need to stay on them indefinitely to keep the weight off, but Ms. Berger maintained the same strict portion control after she stopped taking Mounjaro. It also helped her ease off wine, which some other people taking the drug have noticed as well.

“I learned to find other ways to deal with my stress because I just didn’t have the taste for it,” she said.

Perhaps most important, the drug allowed her to stop obsessing about food and exercise. “Sure, it was expensive,” Ms. Berger said. “But you know what? I saved a lot of money on trainers and not buying wine! To be honest, the most expensive thing so far has been buying new clothes.”