Study: hot bath good for loss of fat mass

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Taking a hot bath several times a week improves the cardiovascular system and induces positive changes in fat tissue, potentially reducing the risk of diabetes and metabolic disorders. But comparing a hot bath to cardio right away…

Hot Bath as Therapy

I must admit, this sounds more appealing to me than cold therapy, which is supposed to increase fat burning. I’d much rather soak in a hot bath than an ice bath. Heat is also often associated with weight loss. Unfortunately, mostly by commercial means. Think of sauna belts and similar products that make you believe you’re burning fat while you’re just losing water weight. It’s as disappointing as realizing you only lost some water weight after drinking a glass of water. New research on obese women with Polycystic Ovary Syndrome (PCOS) suggests that heat, in the form of a hot bath, also has positive effects that go beyond. PCOS is a condition affecting 1 in 10 women of childbearing age. It’s a collection of abnormalities, including hormonal ones. High testosterone levels are common, as well as cyst formation on the ovaries. It’s associated with infertility and increased risk of obesity and diabetes. The causes of such symptoms are often attributed to inflammation and disturbances in fat tissue. However, the results could also be interesting for others at increased risk of metabolic disorders. The findings were presented last week at the annual meeting of the American Physiological Society.

The Effects of a Hot Bath?

The research contributes to the growing knowledge about the benefits of heat therapy. It’s the first study to examine the effects in women with PCOS. It’s also the first to look at changes in fat tissue before and after treatment. Some of these effects are specifically beneficial for women with PCOS. In the study, some women had regular menstrual cycles during the study. However, other effects may also be relevant for other target groups. For the study, six women with PCOS bathed for about two months, three to four times a week, for an hour each time. There are worse studies to participate in. Before and after the study, they analyzed samples of the women’s fat tissue. In addition, they tested insulin sensitivity in four of the women. After the two months, the researchers observed improvements in blood sugar and glucose tolerance, both indicating a reduced risk of developing diabetes. They also saw a decrease in blood pressure and resting heart rate, both indicators of a reduced risk of heart disease. Although some of the improvements occurred after one month, the greatest improvements were seen after two months. The researchers wondered if a hot bath works in some ways similar to cardio. Both work (partly) by increasing temperature. This causes an increase in blood circulation to the skin as a way to cool down.

A Hot Bath as Cardio

Six years ago, I also wondered to what extent a warm bath could lead to the same effects as an active warm-up like running. In that article on the usefulness and functioning of a warm-up, I looked up some relevant studies. Some studies looked at whether core temperature could be increased to the same extent. Indeed, that seems to be the case. Being warmed from the inside seems to have the same effect on core temperature as being warmed by an external source. However, this was not achieved in a study from Australia where only the lower body was immersed in water. However, in a Nigerian study, we also see that other effects of passive or active warm-up are not equal. For example, the effect on the heart differed. Immediately after the bath, no significant increase in heart rate and blood pressure was observed. The total workload of the heart remained the same during the bath. Cardiovascular training literally means training the heart and circulatory system. You don’t train them in the same way by taking a hot bath as you do by actually exercising. This doesn’t seem very strange to me. During activities like running or cycling, circulation is increased not only to bring blood to the skin for cooling. This happens mainly as a way to send more oxygen and glucose to the muscles and to remove waste products. This need doesn’t exist when you’re relaxing in a hot bath. In a study from Austria, other differences were found between an active and passive warm-up, especially in differences in the recovery period after the warm-up. After the active warm-up, they saw that the total oxygen uptake was higher and the amount of lactic acid lower.

“Shock Protein”

However, the latest research provides more insight into the functioning of the benefits that are achieved. The researchers refer to the increase in so-called heat shock proteins in response to the increase in body temperature. These proteins are involved in inhibiting inflammation, repairing damaged insulin receptors, and improving the function and structure of blood vessels. The increase seen in some of these heat shock proteins after the bath may play a role in reducing inflammation and improving insulin sensitivity, as seen in the women. By the way, it is now known that these heat shock proteins also respond to other types of stress such as cold. So if you prefer to jump into an ice bath, go ahead.

References

• Experimental Biology 2018. “Soaking in hot tub improves health markers in obese women: Heattherapy appears to reduce inflammation, improve insulin resistance and lessen effects of polycystic ovary syndrome.” ScienceDaily. ScienceDaily, 24 April 2018.