• Posted July 27, 2026

'Yo-yo' Weight Loss Linked To Decline In Muscle Mass

Middle-aged folks have a higher risk of muscle loss if their weight “yo-yos” due to inconsistent dieting, a new study says.

People who repeatedly dropped and regained weight wound up losing nearly four times as much thigh muscle during a four-year period compared to others whose weight remained relatively steady, researchers recently reported in the journal Radiology.

“When people’s weight cycled, they lost tremendous amounts of muscle along with the fat, and they didn’t gain the muscle back,” said lead researcher Dr. Thomas Link, a professor of radiology at the University of California-San Francisco.

“This tells us that understanding how to protect muscle while people are losing weight is important for overall health,” he said in a news release.

Recent studies have reported that people who stop taking a GLP-1 weight-loss drug like Ozempic or Zepbound regain approximately two-thirds of the weight they lost, researchers said in background notes.

There also have been concerns that people on GLP-1 drugs tend to lose muscle mass along with body fat as they drop weight, researchers said.

"Fat loss is just one piece of a much larger puzzle that includes how weight loss affects arthritis, muscle, bone and other factors," Link said. "As more people use effective weight-loss therapies, we need to be thinking about how those pieces fit together.”

To investigate these concerns, researchers analyzed MRI scans and health data from more than 1,400 middle-aged people participating in a long-running study of knee arthritis.

Most of the people maintained a stable weight during a four-year period, but nearly 80 experienced yo-yo weight loss and gain, researchers said.

MRI scans showed that people whose weight cycled lost nearly 4% of their thigh muscle volume, compared with about 1% among those whose weight remained stable.

These results suggest the people rapidly losing weight through either diet or GLP-1 drugs need to focus on preserving muscle, researchers said.

“We need to better understand how weight loss affects the body in ways that aren’t about the number on the scale,” Link said.

More information

Harvard Medical School has more on maintaining muscle while losing weight.

SOURCES: University of California-San Francisco, news release, July 21, 2026; Musculoskeletal Imaging, July 21, 2026