A new study has found that taking a dip in ice water may reduce bad body fat in men and reduce the risk of diseases such as diabetes.
Researchers studied 104 studies and found that many of them reported significant effects from swimming in cold water, including also on good fats that help burn calories.
They suggest that this may protect against obesity and cardiovascular disease.
But the review was generally inconclusive about the health benefits of cold water bathing, an activity that is gaining popularity.
The research team from UiT The Arctic University of Norway and from Northern Norway University Hospital say it is unclear whether winter swimmers are in better health.
Lead author James Mercer, of UiT, said: “From this review, it is clear that there is increasing scientific support that voluntary exposure to cold water may have some beneficial health effects.
Several studies have shown significant effects of cold water immersion on various physiological and biochemical parameters.
But it is difficult to assess the question of whether these are beneficial to health or not.
“Based on the results of this review, many of the purported health benefits from regular exposure to cold may not be causal.
Alternatively, it could be explained by other factors including an active lifestyle, trained stress handling, social interactions, as well as a positive mindset.
“Without further conclusive studies, the topic will remain a topic of debate.”
The review indicated a positive association 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 that stores energy.
The study found that exposure to cold in water – or air – also appears to increase production of the protein adiponectin by adipose tissue.
This protein plays a key role in protecting against insulin resistance, diabetes and other diseases.
According to the results, repeated immersion in cold water during the winter months significantly increased insulin sensitivity and lowered insulin concentrations.
Much of the available research has involved small numbers of people, often of the same sex, with varying water temperatures and salt levels.
The new study notes that weight loss, improved mental health, and increased libido are among the many health and well-being claims made by adherents of regular immersion in cold water or arising from anecdotal cases.
It can take many forms such as swimming in cold water during the winter, and is the subject of increasing interest around the world.
The main objective of the review was to determine whether voluntary exposure to cold water has health effects in humans.
The researchers excluded studies in which people were wearing wetsuits, casually immersed in cold water, and water temperatures above 20°C.
However, they say education is also essential about the health risks associated with diving in icy waters.
These include the effects of hypothermia, and heart and lung problems often associated with shock from a cold.
The results were published in the International Journal of Polar Health.