An icy swim may reduce ‘bad’ body fat, but other health benefits are unclear – review of current science suggests


Diving in cold water can reduce ‘bad’ body fat in men and reduce the risk of conditions such as diabetes, suggests a major scientific review published in the peer-reviewed magazine International Journal of Circumpolar Health.

The authors say that many of the 104 studies they analyzed showed significant effects of cold-water swimming, including also on “good” fats that help burn calories. This may protect against obesity, cardiovascular disease, they add.

However, the review was inconclusive overall on the health benefits of cold water bathing, an increasingly popular pastime.

Much of the available research involved small numbers of participants, often of one sex, and with differences in water temperature and salt composition. Also, it is unclear whether winter swimmers are naturally healthier, according to the team of scientific experts comprising authors from the UiT journal The Arctic University of Norway and the University Hospital of North norway.

“From this review, it is clear that there is growing scientific support that voluntary exposure to cold water may have beneficial health effects,” says lead author James Mercer, of the Uit.

“Many studies have demonstrated significant effects of cold water immersion on various physiological and biochemical parameters. But whether or not these are beneficial to health is difficult to assess.

“Based on the results of this review, many health benefits claimed from regular exposure to cold may not be causal. Instead, they may be explained by other factors, including a active lifestyle, trained stress management, social interactions, as well as a positive attitude.

“Without further conclusive studies, the subject will continue to be debated.”

Weight loss, better mental health, and increased libido are among the many health and wellness claims made by regular cold water immersion enthusiasts or stemming from anecdotal reports.

This activity takes many forms such as swimming in cold water during the winter, and is the subject of growing interest all over the world.

The main objective of the review was to determine whether voluntary exposure to cold water has any effects on human health. The methodology involved a detailed search of the scientific literature.

Studies in which participants wore wet suits, accidental immersion in cold water, and water temperatures above 20 degrees centigrade were excluded from the review.

Topics covered by studies eligible for review included inflammation, adipose tissue, blood circulation, the immune system, and oxidative stress.

Immersion in cold water has a major impact on the body and triggers a shock reaction such as an elevated heart rate.

Some studies have provided evidence that cardiovascular risk factors are actually improved in swimmers who have adapted to the cold. However, other studies suggest that the workload on the heart is further increased.

The review provided information on the positive links between swimming in cold water and brown adipose tissue (BAT), a type of “good” body fat that is activated by cold. BAT burns calories to maintain body temperature unlike “bad” white fat which stores energy.

Exposure to cold in water – or air – also appears to increase the production of adiponectin by fatty tissue. This protein plays a key role in protecting against insulin resistance, diabetes and other diseases.

According to the review, repeated immersions in cold water during the winter months significantly increased insulin sensitivity and decreased insulin concentrations. It was for inexperienced and experienced swimmers.

However, the authors point out that the profile of the swimmers participating in the studies varied. They ranged from elite swimmers or established winter swimmers to those with no winter swimming experience.

Others weren’t strictly ice bathers, but used cold water immersion as post-treatment exercise.

Education is also needed about the health risks associated with swimming in freezing water, say the authors. These include the consequences of hypothermia and heart and lung problems that are often linked to cold shock.


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Richard V. Johnson