There's two aspects to this, first it improves blood circulation, and second, it stimulates the production of dark or brown fat, which also increases your metabolism and helps you burn fat reserves more efficiently, so you lose weight once the winter cycle is complete:
- Exposure to cold temperatures causes stem cells to form brown fat instead of white fat, according to a new study.
- Brown fat causes our bodies to burn extra calories to keep warm — so if we can produce brown instead of white fat, that could help us burn off excess body fat.
- This adds to the body of knowledge demonstrating that exposure to the cold might have real health benefits.
If you want to lose weight, you might consider getting comfortable with the cold.
A new
study published in the Nature journal Scientific Reports has found evidence that exposure to cold temperatures could transform the type of fat we form in our bodies, and even potentially help us burn off excess body fat.
For the research, scientists differentiated stem cells (which can become other types of cells) to become fat cells at both normal body temperature and at a slightly cooler temperature. They found that at the lower temperatures, the cells formed a kind of fat known as brown fat, which causes bodies to burn more calories to keep warm and burn off excess body fat.
People always have some layer of fat in their bodies. Adults have mostly white fat, which serves as a sort of solid, inert way of storing energy. White fat is what makes up dangerous excess body fat. Brown fat, on the other hand, is used to rev up the metabolism to keep us warm — it's how babies regulate their body temperature, since they don't have the muscles to shiver themselves warm yet.
“Cold exposure increases the amount of brown fat that is present in the body,” says Cannon, who has published
research on brown fat and its health benefits.
So while the body’s first response to cold is to shiver, it eventually makes and activates enough brown fat to take over those heat-producing responsibilities, she explains. In either case, your body is burning extra calories in response to cold. That can even translate to some body-weight benefits. As long as you’re not overeating to make up for the extra energy your cold-exposed body is using up, you can expect to lose some weight in response to cold, Cannon says. (How much depends on the person.)
There may be some additional metabolic benefits. Among people with higher levels of brown fat, “we see better insulin sensitivity, lower levels of circulating fatty acids and also lower levels of triglycerides,” says Sven Enerbäck, a professor of cell biology at Sweden’s University of Gothenburg whose
research suggests that people’s stores of brown fat change (and mostly decline) as they age.
Enerbäck says the healthy metabolic shifts associated with brown fat are in some ways just the opposite of what happens in people with type 2 diabetes. There’s some excitement among scientists that cold exposure and brown-fat genesis could be used to counteract or prevent diabetes, obesity and other metabolic disorders.
Benefits of swimming in colder water:
Summary
The Scandinavian winter-swimming culture combines brief dips in cold water with hot sauna sessions, with conceivable effects on body temperature. We study thermogenic
brown adipose tissue (BAT) in experienced winter-swimming men performing this activity 2–3 times per week. Our data suggest a lower thermal comfort state in the winter swimmers compared with controls, with a lower core temperature and absence of BAT activity. In response to cold, we observe greater increases in cold-induced
thermogenesis and supraclavicular skin temperature in the winter swimmers, whereas BAT
glucose uptake and muscle activity increase similarly to those of the controls. All subjects demonstrate nocturnal reduction in supraclavicular skin temperature, whereas a distinct peak occurs at 4:30–5:30 a.m. in the winter swimmers. Our data leverage understanding of BAT in adult human
thermoregulation, suggest both heat and
cold acclimation in winter swimmers, and propose winter swimming as a potential strategy for increasing energy expenditure.
Graphical abstract