Eileen Isotalo was always able to lose weight, but always gained it back. Now 66, her first diet was with Weight Watchers at age 14. She went on to try one diet after another and bought so many books on weight loss that she thinks she has more than the public library.

In desperation, she finally went to a weight management clinic at the University of Michigan. She had sleep apnea and aching knees, but could not curb her appetite.

“It’s just this drive to eat,” said Ms. Isoltalo, a retired interior design coordinator. “It’s almost like this panic feeling when you start craving food.”

“My mental shame was profound,” she said.

Now, though, since she started taking Wegovy, one of a new class of drugs for obesity that was prescribed by her doctor at the clinic, those cravings are gone. She has lost 50 pounds and jettisoned the dark clothes she wore to hide her body. Her obesity-related medical problems have vanished along with much of the stigma that caused her to retreat from family and friends.

But like others at the clinic, she still struggles with the fear others will judge her for receiving injections to treat her obesity rather than finding the willpower to lose weight and keep it off.

Yet the drug, she said, “changed my life.”

Wegovy and drugs like it make this “a very exciting time in the field,” said Dr. Susan Yanovski, co-director of the office of obesity research at the National Institute of Diabetes and Digestive and Kidney Diseases.

About 100 million Americans, or 42 percent of the adult population, have obesity, according to the Centers for Disease Control and Prevention. For the first time, people with obesity, who faced a lifetime of medical jeopardy, can escape the ruthless trap of fruitless dieting and see their obesity-related health problems mitigated, along with the weight loss.

But there is still the taint.

“There’s a moral component to it,” Dr. Yanovski said. “People really believe that people with obesity just need to summon their willpower and they think that taking a medicine is the easy way out.”

Unlike other chronic diseases, obesity is on full public display, Dr. Yankovski said. “No one looks at you and knows you have high cholesterol of high blood pressure,” she said.

Obesity, she added, “is one of the most stigmatized conditions out there. “

Wegovy and a similar but less effective medication, Saxenda, are the only ones in their class of drugs so far to be approved for the treatment of obesity — others like Ozempic and Mounjaro are diabetes drugs but also spur weight loss.

Novo Nordisk, Wegovy’s maker, reports that doctors in the United States have written about 110,000 prescriptions for the drug. Citing a huge demand, the company recently put its advertising for Wegovy on hold.

“We can’t make enough,” said Ambre James-Brown, a Novo Nordisk spokeswoman. Supplies are so limited that the company is only selling the drug in the United States, Norway and Denmark, the company’s corporate headquarters. Its high list price of $13,492 a month puts it out of reach for most whose insurance will not cover it. But increasingly many insurers do.

The drugs have arrived at a time when researchers have documented the risks of obesity and the futility of prescribing only diet and exercise as a treatment. Decades of studies have consistently shown that very few people can lose excess weight and keep it off with lifestyle changes alone.

People with obesity are at risk for a variety of serious medical conditions, including diabetes, hypertension, high cholesterol, sleep apnea and nonalcoholic fatty liver disease, a leading reason for liver transplants in the United States.

Losing weight can make some of these complications vanish.

Yet the belief persists — fed by diet gurus, influencers and an industry selling supplements and diet plans — that if people really really tried, they could shed pounds.

So those who take a drug like Wegovy often end up in uncomfortable situations that are influenced by the common view that obesity is a lifestyle choice.

At the University of Michigan clinic there are those like Ms. Isotalo whose reluctance to admit to taking Wegovy stems from her conviction that those who take it are often thought to be cheating.

Another patient, though, Katarra Ewing of Detroit, readily tells anyone who asks that she takes the drug. She tried diets, but it was Wegovy that allowed her to lose 90 pounds.

She came to the weight management clinic after her all-night shift at a Ford factory, ebullient and vibrant, wearing a vivid green sweater. She has more energy now that she lost the weight, her mood is brighter, her high blood pressure gone.

But she discovered an unintended social consequence to weight loss, as many longtime friends fell away.

“Only my genuine friends are left and that’s a very small number,” Ms. Ewing said.

Obesity medicine specialists say they are not surprised — they see the same thing after people lose weight with bariatric surgery.

Relationships shift because obesity is such a defining condition. People of normal weight may feel superior to a friend with obesity and that helps define a relationship — until the friend loses weight. Other friends who themselves have obesity may use the condition as a bonding factor in the relationship. Now that is gone.

Another issue is the drugs’ reputation as vanity medications, which has been amplified by comedians’ punchlines at the Oscars and in other high-profile settings.

But when Samuel Simpson came to the weight management clinic, he considered losing weight to be a matter of life or death.

Mr. Simpson was terrified he’d face the fate of his mother, brother and sister, all of whom had obesity and diabetes. They all developed kidney failure that ultimately killed them, each dying at the age of 59.

His first appointment with Dr. Amy Rothberg at the clinic was nearly two years ago, when he was 58. He had obesity and diabetes. Although he was taking high doses of insulin to lower his blood sugar, his kidneys were starting to fail.

“I was so afraid,” he said. “Was I going to end up on dialysis like everyone else? I’d be history.”

He began with a diet and then Dr. Rothberg added Mounjaro, a drug by Eli Lilly that appears to be even more powerful than Wegovy in eliciting weight loss, but is, so far, only approved for people with diabetes.

Now he’s lost 44 pounds, 20 percent of his original weight, and his diabetes is in remission. The weight loss, he said, “turned my life around.”

He will tell those who ask how he lost the weight,

“I’m not like the roadside preacher but when someone asks me how I did this I will tell them,” he said.

Art Regner had a different issue. A garrulous color commentator for the Detroit Red Wings hockey team, he said he was not ready to resort to medication. But when he came to Dr. Rothberg’s clinic he was chagrined. He’d regained 22 of the 76 pounds he lost by dieting.

Dr. Rothberg, who is also the medical director of Rewind, a company that counsels diabetic patients, suggested Wegovy or Mounjaro. But Mr. Regner felt he should have enough willpower to do it on his own. He knows his blood sugar is high and is aware of the consequences of diabetes.

Dr. Rothberg gently explained to him that it was not his fault he kept regaining weight every time he lost some.

“I think biology is conspiring against you,” she said. “I don’t think it’s a matter of willpower.”

Mr. Regner was not swayed. “I believe in myself,” he said. “I wake up in the morning and look in the mirror and say, ‘Are you going to do it or aren’t you?’”