No one likes being cold, so Franois Haman, a professor at the University of Ottawa, Canada, avoids recruiting too many people for his studies on the benefits of chilled body temperature.

The human body is not designed to endure the cold. In his experiments, Haman noted that even fully dressed individuals could not sustain the cold at 7 degrees Celsius (44.6 degrees Fahrenheit) for a whole day.

Before the Industrial Revolution, Haman explained that the cold and hot temperatures during different seasons that humans endured affected the body's metabolic health.

According to researchers, cold causes the body to react by producing new fat and changing muscles. This explains why people with diabetes and other metabolic diseases seem to benefit from the cold weather. However, the effects of cold on modern human health are still unclear.

For Haman, the idea of freezing is one of the fascinating scientific stimuli he's studied. Despite the interest in heat, he noted that even though it gets scorching, he generally survives as long he has access to water and shades.

According to Haman, the key to surviving in extreme weather is having the right equipment and working together with others. Through his studies, he learned how the body responds to different conditions.

Catecholamines

Every day, Haman begins his day with a cold bath or shower. This activates a hormone known as catecholamines, which can trigger a fight or flight response in the body.

However, catecholamines are stress hormones. Haman stated that humans are exceptionally ill-equipped to endure cold. For instance, humans have gangly feet and arms that extend to distant toes. Humans mainly rely on blood to keep their bodies warm. When the cold is too extreme, the bodies will sacrifice blood flow from human limbs to preserve the core temperature.

At rest, humans can generate up to 100 watts of heat. However, if they're not supplying enough heat to the environment, their body's response to maintain its equilibrium can fall apart. This causes the skin to lose its heat gradually. The first instinct is to try to find warmth. It becomes physiological when the temperature drops by a couple of degrees. When it gets physiological, people start to shiver, and their teeth chatter. 

The "brown fat"

Other animals, such as squirrels and mice, are designed to generate heat using brown fat. This type of tissue burns calories to generate heat.

Scientists initially thought that brown fat was exclusive to rodents. However, in 2009, studies revealed that brown fat is found in adult humans. In his research in 2013, Haman discovered that low-intensity exposure to cold could stimulate the production of more brown fat. 

Brown fat doesn't just sit there and absorb the cold. It also produces a variety of chemicals that help the body retain its heat. 

Other laboratories have tried to study the effects of brown fat on different metabolic processes. In rodents, cold temperatures can trigger the production of fat and glucose. Some of these studies suggest that the tissue can protect the body from the harmful effects of dysfunctional glucose processing.

Brown fat and diabetes

After learning about the brown fat effect on diabetes, Joris Hoeks of the Maastricht University of the Netherlands conducted a study to study how cold affects the body's ability to control blood sugar. For ten days, participants were subjected to a cold environment. Their blood sugar levels significantly dropped when they were subjected to cold weather.

After exposing the participants to cold temperatures, Hoeks noticed that their insulin response changed. However, he couldn't pinpoint a link between the cold and brown fat activity.

In a follow-up study in 2021, the researchers tried to replicate the experiment in cold conditions. Instead of brown fat, the cold-inflicted muscle cells exhibited similar changes to those that occur in people with diabetes. According to Hoeks, these changes could help the body obtain more glucose by producing small muscle fibers designed to transport the fuel.

Although the study results supported the notion that cold acclimation can improve humans' health, further studies are still needed to investigate the effects of varying degrees of exposure on different body parts. For now, Haman wants to study how varying degrees of exposure can affect weight loss.