(WGN Radio) – Recently approved weight loss drugs like Wegovy and Zepbound have shown promising results, helping patients lose 15% to 25% of their body weight. But despite that promise, these medications are not a once-and-for-all solution to obesity, experts say.

People who stop taking the drugs have noticed a “rebound effect.”

“The problem is when people stop taking the medication, they’ll gain their weight back. We haven’t come up with something that is permanent yet,” explained Dr. Jeffrey Kopin, chief medical officer of Northwestern Medicine Lake Forest Hospital.

Wegovy and Zepbound’s injections work similarly to Ozempic and Mounjaro, which are also in high demand right now. The drugs imitate the hormones that regulate appetites by communicating fullness between the gut and brain when people eat.

But those changes aren’t permanent. Once someone stops injecting the drugs, they no longer feel the effects.

A study, published in the Journal of the American Medical Association in 2021, looked at overweight and obese adults taking semaglutide (the active ingredient in Ozempic and Wegovy) for 20 weeks. Those who kept going after the 20-week period continued to lose weight, ultimately losing about 17% of their body mass on average over 68 weeks. Meanwhile, those who switched to a placebo at 20 weeks started to regain the weight they had lost, ending just 5% lower than where they had started.

Another study, published in August 2022, found that one year after participants stopped taking semaglutide, they regained two-thirds of the weight they had lost.

The study published in JAMA emphasized that obesity is a chronic condition, and therefore needs chronic treatment.

“Some people don’t have an awareness that this might have to be a medication that will be lifelong,” Dr. Alexandra Sowa, a doctor and NYU School of Medicine clinical instructor, told the Wall Street Journal.

“I think for somebody who’s at high risk of bad things happening because of their weight – somebody who has diabetes, somebody who is about to get diabetes, they’re way overweight, they’ve tried everything to lose weight – it would be good to lose weight, and the medication is going to help with that,” Kopin said.

However, someone who hasn’t tried to lose weight on their own may want to give it a serious try first, to avoid becoming dependent on the medication, he said.

Kopin said these types of decisions should be made on a case-by-case basis, and in consultation with a health care professional.

Hear more from Dr. Kopin, including the impact of drugs like Ozempic and Wegovy on smoking addiction and alcohol cravings, in the audio player below.

While the drugs have shown promising results, the cost of these injectables has largely limited them to the wealthy. A monthly supply of Wegovy rings up at $1,300 and Zepbound will put you out $1,000. Shortages for the drugs have also limited the supplies. Private insurers often do not cover the medications or place strict restrictions on who can access them.

The Associated Press contributed to this report.