An obesity drug Jillian Michaels hates does help you lose weight - but the effects stop when you stop taking it

• Jillian Michaels urged people to use diet and exercise for weight loss instead of medication.
• The drug semaglutide has shown promise for treating obesity but is still being researched.
• Michaels' comments perpetuate dangerous myths about obesity, according to experts.

Celebrity fitness guru Jillian Michaels is speaking out against a promising new obesity medication, saying that lifestyle changes are a better method of weight loss with fewer side effects.

Michaels, who rose to fame as a trainer on the controversial weight-loss reality-TV show "The Biggest Loser," argued that the drug, semaglutide, may have unforeseen side effects and that the weight-loss results aren't sustainable.

In a recent study, semaglutide was found to help people with obesity lose about 15% of their weight in 68 weeks.

"These results are not game-changing," Michaels said in a video posted on Instagram. "What's game-changing is exercise and proper nutrition."

Experts told Insider that Michaels was also perpetuating misconceptions about obesity.

Evidence suggests people lose weight on semaglutide but regain if they stop taking it

Since Michaels' comments, there's even more evidence to support semaglutide for weight loss, at least while patients are taking the drug.

In a recent study published in JAMA, patients who took the drug for 20 weeks lost about 10% of their body weight, on average. One group then continued to take the drug, while the other was put on a placebo.

Researchers found the placebo group gained back nearly all the weight they lost, while patients who kept taking semaglutide lost another 8% of their body weight, on average.

These findings support previous research that semaglutide has significant potential for supporting weight loss, but patients must continue to use the medication to enjoy its benefits.

Semaglutide has side effects, but it's no riskier than medications for diseases like hypertension

Semaglutide was approved to treat Type 2 diabetes in 2017 and is usually given as a weekly injection. Researchers have been studying whether it can help treat obesity since it can reduce body fat and suppress appetite.

Michaels said in the video that she was wary of the risks of semaglutide and of evidence suggesting people could regain weight once they stop taking the drug.

That's made her an unlikely ally to health experts who normally object to Michaels' emphasis on weight loss at any cost.

"This is the first time I will say I agree with Jillian Michaels," said Rachael Hartley, a registered dietitian who specializes in intuitive eating and the author of a new book called "Gentle Nutrition."

The medication works by boosting insulin production and increasing appetite-suppressing hormones, causing some experts to worry that it may have long-term consequences.

"I get really concerned about a medication in which the method of action is putting the pancreas into overdrive," Hartley said.

Dr. Scott Butsch, the director of obesity medicine at the Cleveland Clinic, said that the side effects of semaglutide were no riskier than those of medications used to treat other chronic conditions like hypertension, diabetes, and high cholesterol. That's true even if people continue the medications to maintain the weight loss.

The difference, he said, is that people are resistant to think of obesity as a disease and treat it as such.

Michaels said weight loss is 'not hard to do' with diet and exercise

Participants in the recent study on semaglutide who took the drug lost an average of 34 pounds total - about half a pound per week.

Michaels said in the video that losing a comparable amount of weight with diet and exercise was "not hard to do," suggesting cutting an average of 300 calories a day (roughly equivalent to a Frappuccino).

This suggestion is based on a common myth in nutrition that cutting 3,500 calories is equivalent to losing a pound of body weight or fat, Hartley said. While a calorie deficit is necessary for weight loss, a variety of factors influence how a person will lose weight, making blanket recommendations unhelpful, she said.

Michaels also recommended exercise for creating a calorie deficit. But it takes a lot of exercise to instigate weight loss without making dietary changes. And research suggests that exercising solely for weight loss can sometimes backfire, prompting people to eat back the calories they burned.

Butsch said that while lifestyle changes could lead to weight loss for some people, insisting on diet and exercise could leave people feeling as if they've failed if they can't lose weight with these methods. It can also discourage people from seeking other forms of treatment such as bariatric surgery or medication.

"That doesn't replace trying to live a healthier life, eat healthier foods, exercise regularly, but it recognizes that people are different from one another and don't necessarily respond in a similar fashion to a treatment," he said.

It's not always possible to 'see' someone's health

In the video, Michaels talked about people "choosing" not to change. She said that if diet and exercise aren't working, it's because people aren't doing it enough or correctly.

Hartley said that while changing diet and exercise habits could be a healthy choice for some people, it's not one size fits all. Promoting lifestyle solutions for obesity can sometimes do more harm than good, as weight stigma is linked to eating disorders and yo-yo dieting.

"Jillian Michaels and, unfortunately, the majority of healthcare providers have the assumption that you can visually see someone's health," Hartley said. "There's an assumption that if you're higher weight, you're doing something wrong, and frankly that's not true. Body diversity naturally exists."