To Trim Fat, Turn Down the Thermostat

Brown adipose tissue is a specialized form of fat tissue that produces heat by burning energy to maintain the body’s core temperature. Previously, a team from Virginia Commonwealth University (Virginia, USA) observed that acute cold exposure promotes intercellular communication between skeletal muscle and brown fat tissue that is mediated by an exercise-induced hormone. This metabolic signaling may help the body more efficiently maintain its core temperature.  Francesco S. Celi and colleagues report that their current study suggests that a cooler sleeping environment may be sufficient to expand brown adipose tissue mass and activity, whereas  exposure to warm temperatures result in suppression of this tissue The researchers enrolled five healthy, lean male volunteers in a four-month long study in which subjects slept in a researcher center in temperature-controlled rooms, while resuming normal activities during the day.  During the first month, the overnight temperature was "neutral" at roughly 75 degrees. The next month it was cooled to 66 degrees; for the third, it went back to 75 degrees; and finally, for the fourth, it was 81 degrees.  At the end of each month the volunteers underwent metabolic testing in the metabolic chambers at 75 degrees and 66 degrees. After four weeks of sleeping at 66 degrees, the team noted double the volume of brown fat, and insulin sensitivity improved. Writing that:  “Circulating and adipose tissue, but not skeletal muscle, expression levels of leptin and adiponectin displayed reciprocal changes concordant with cold-acclimated insulin sensitization,” the study authors submit that: “These results suggest regulatory links between [brown adipose tissue] thermal plasticity and glucose metabolism in humans, opening avenues to harnessing [brown adipose tissue]for metabolic benefits.”