Cryotherapy Pictured here, French soccer player Franck Ribery doing cryotherapy. AP Photo/Franck Fife, Pool

Top athletes, including LeBron James and Cristiano Ronaldo, are big fans of cryotherapy, as are actresses Mandy Moore and Mika Kelly, dance star Derek Hough and a host of other celebrities.

The treatment involves going into a whole body chamber that exposes the body to temperatures of minus 150 to minus 290 degrees Fahrenheit. It purportedly helps muscles recover after a tough workout, in addition to helping to ease chronic pain, depression, migraines and other serious illnesses and conditions.

However, the Food and Drug Administration today said that there isn't any proof the whole body cryotherapy has any health benefits — and that it actually poses risks.

The FDA issued a consumer update about whole-body cryotherapy, urging people to beware of misleading claims from spas and gyms about the treatment.

"Based on purported health benefits seen in many promotions for cryotherapy spas, consumers may incorrectly believe that the FDA has cleared or approved WBC devices as safe and effective to treat medical conditions," Dr. Aron Yustein, a medical officer in the FDA’s Center for Devices and Radiological Health, said in the update. “That is not the case.”

Not even one whole body cryotherapy machine has actually been approved by the FDA for medical treatment, the agency said.

The FDA also said that there is no evidence that whole body cryotherapy can improve circulation, boost metabolism, improve recovery and soreness after workouts, and relieve joint and body pain.

"Given a growing interest from consumers in whole body cryotherapy, the FDA has informally reviewed the medical literature available on this subject," Yustein said in the consumer update. "We found very little evidence about its safety or effectiveness in treating the conditions for which it is being promoted."

If someone is thinking about trying whole body cryotherapy, the FDA recommends they talk to their physician beforehand.

The agency warned that the machines can potentially be dangerous, putting people at risk of asphyxiation, particularly when liquid nitrogen is used for cooling.

Additionally, cryotherapy participants are at risk of frostbite, burns and eye injury from the extreme temperatures, the agency said.