As winter approaches and temperatures drop, many of us reach for the thermostat or wrap up in warm layers. But new research suggests that embracing the cold could have significant health benefits, particularly in the fight against obesity and type 2 diabetes. The secret lies in a special type of fat known as brown fat, which burns calories to generate heat when we are cold.
Unlike white fat, which accumulates around the thighs, waist, and hips, brown fat acts as an internal heater. Babies are born with plentiful stores of it, as they cannot shiver to keep warm. Brown fat cells are rich in mitochondria, but instead of producing energy currency for the body, they contain a protein called UCP1 that converts calories directly into heat. According to Michael Symonds, professor of developmental physiology at the University of Nottingham, when stimulated, brown fat can produce 300 times more heat per unit mass than any other tissue.
For decades, scientists believed brown fat disappeared after infancy, but a 2009 study from Finland and Sweden revealed that adults retain it. When temperatures drop below 16C, brown fat becomes active and absorbs glucose and fats from the bloodstream. Further evidence emerged in 2021, when researchers at The Rockefeller University examined PET scans of over 52,000 people. They found that those with brown fat had lower rates of type 2 diabetes, heart disease, stroke, and high blood pressure, as well as better insulin sensitivity and lower levels of glucose and triglycerides.
The findings have sparked interest in harnessing brown fat for weight loss. Simple methods such as cold showers, icy baths, or consuming spicy foods and caffeine are thought to activate it. However, experts caution that more research is needed to confirm whether these effects translate into meaningful health improvements in the long term. While the hype may be promising, it is worth exploring the evidence before plunging into an icy lake.
