Hot tubs have many benefits, but is weight loss one of them?

If you enjoy sitting in the warm, churning water of a hot tub, you're not alone. A growing number of Americans are getting hot tubs, pools and spas for at-home use - as much as 17% of the country, according to Statista. Hotels are similarly including hot tubs and Jacuzzis in more rooms and private balconies as a luxury upgrade for vacationers. 

While most people know that soaking in a hot tub feels good and can be relaxing, fewer people may understand that there are health benefits and a few risks associated with soaking in the bubbling water - particularly for lengthy periods of time and for people with certain medical conditions. Before your next hot tub soak, it may be helpful to know which benefits and risks are real, and which ones have been overstated. 

Are hot tubs good for you? 

The first thing to understand is that there are many studied benefits associated with using hot tubs. "A wide variety of health benefits have been observed from regular hot tub use," says Tom Cullen, PhD, an assistant professor in the Centre for Physical Activity at Coventry University in England. He says the most consistently observed of these relates to improved cardiovascular health because hot water can help with circulation, lower blood pressure and reduce artery stiffness.

Soaking in a hot tub before bed can also help with sleep. "When we fall asleep, our body temperature drops as most functions slow down or cease," explains Dr. Rajkumar Dasgupta, a clinical associate professor at the University of Southern California and the chief medical advisor for Garage Gym Reviews. He says that entering a hot tub 1-2 hours before bedtime first heats the body and then stimulates this natural cooling process upon exiting the warm water. "As the body cools, it prepares the body for sleep by signaling the brain that bedtime is near," he explains.

There are mental health benefits as well. "Feeling the warmth of water can help to temporarily calm the nervous system and soothe our senses, which helps reduce stress and promote relaxation," says Erin Engle, PsyD, a clinical psychologist at the NewYork-Presbyterian/Columbia University Irving Medical Center. She says a hot tub can also be a useful place to practice mindfulness and slow down from the stressors of the day. 

Other benefits of soaking in a hot tub include relief from muscle and joint pain and improved recovery following a workout. Arthur Cheng, PhD, an assistant professor in the Muscle Health Research Centre at York University in Toronto, says that soaking in hot water can help one's muscles recover faster, especially "after prolonged endurance exercise."

But the experts caution that not all purported benefits associated with hot tub use are proven. "While soaking in a hot tub offers many sound health benefits, some that circulate may lack scientific backing," says Dasgupta. Claims about detoxification that purportedly occurs through heat-induced sweating and improved outcomes from chronic illnesses, for instance, "are often overstated." 

Can soaking in a hot tub burn calories? 

Another area to exercise restraint is in overstating benefits related to weight loss. Despite claims that one can "forget" physical exercise because sitting in a hot tub for 30 minutes "could be just as beneficial for health as going for a run," there's a big difference between sitting in hot water and engaging one's cardiovascular system through aerobic exercise. 

Cullen co-authored the study that claims like these are based on and says that, while it's true that one can burn 100 or so calories by sitting in a hot tub for 30 minutes, "exercise is superior and leads to many benefits which heating does not." Some of these superior benefits include "reductions in body weight and strengthening of muscles and bones." 

At the same time, passive heating via a hot tub or sauna can mimic low-intensity exercise by raising your heart rate 20-40 beats per minute, "which would be the equivalent of going out for a brisk walk," says Cheng. "But we should be careful about making grand assumptions that taking a soak in a hot tub replaces exercise because you can raise your heart rate to a much higher extent during exercise to cause greater improvements in cardiovascular fitness," he adds.

Is it dangerous to be in a hot tub?

It's also worth noting that hot tubs aren't recommended for everyone and that "certain groups of people are advised not to use hot tubs," says Cullen. These include "the elderly, young children, and pregnant women." This is because an elevated body temperature can be dangerous to such groups, and hot tubs not only increase one's core temperature but also make it difficult for the body to cool down through sweating. 

This is why the Centers for Disease Control and Prevention (CDC) notes that hot tub water temperature for everyone, "should not exceed 104 degrees." 

Hot tubs are also generally recommended against for people with cardiovascular or respiratory conditions, anyone who has experienced an allergic reaction or skin condition from chemicals used in water treatment, and for people who have peripheral neuropathy - a condition common among patients with diabetes that decreases sensitivity in lower extremities. 

The CDC also recommends having water chlorine and pH levels checked in hot tubs "at least twice per day," and steering clear of hot tubs that smell. "A well-chlorinated hot tub has little odor," the agency cautions. "A strong chemical smell indicates a maintenance problem." 

Hot tubs, particularly frequently used ones, can also breed infection-causing bacteria and should be avoided by anyone with open sores or wounds. "Prolonged exposure to hot water can also lead to symptoms like dehydration and dizziness," Dasgupta adds. To minimize risks, he suggests one "follow safety guidelines, limit soak times, stay hydrated, choose hot tubs that are regularly cleaned and maintained, and ask your doctor before using, if unsure."

More:Looking to improve your mood and sleep better? Experts say to take more baths.