Daily wisdom: heat up your metabolism

Exposure to cold has long been proven to increase your caloric burn. This has to do, in part, a special type of tissue called brown fat, says Matt Robinson, Ph.D., assistant professor of exercise physiology and biology at Oregon State University. Brown fat has unusually dense mitochondria with high amounts of something called uncoupling proteins (UCPs). UCPs actually make mitochondria less efficient, so they need more fuel to produce the same amount of energy (like a car that gets lower gas mileage). Most types of tissue burn fat and carbs via contractions and therefore aren't able to work in the cold, but brown fat oxidizes its fuels, a process which can continue at lower temperatures. And with higher fuel oxidation, your metabolism increases, Robinson explains.

But it’s really exposure to both ends of the temperature spectrum that helps deliver that extra boost, according to the research. "Our bodies are designed to maintain a constant state of equilibrium, known as homeostasis," explains Paul Arciero, Ph.D., director of the Human Nutrition & Metabolism Laboratory at Skidmore College in New York. Disrupting this state by alternating between higher or lower temperatures means your metabolism activates to cool you down or stay warm. And while the study looked at obese and diabetic populations, Arciero says temperature fluctuations can help fit folks burn more calories, too.