Why all these praise of the cold climes? According to three preliminary studies published Wednesday in the New England Journal of Medicine, Cold could activate these brown fat to burn and keep us lean and mean fighting machines that we are supposed to be! But again the research shows it is easier for healthy men to loose weight!
The preliminary studies included 24 healthy men;
10 who were lean (body-mass index [BMI] [the weight in kilograms divided by the square of the height in meters], <25).
14 who were overweight or obese (BMI, =25)
Under thermoneutral conditions (22°C) and during mild cold exposure (16°C). Putative brown-adipose-tissue activity was determined with the use of integrated 18F-fluorodeoxyglucose positron-emission tomography and computed tomography.
Body composition and energy expenditure were measured with the use of dual-energy x-ray absorptiometry and indirect calorimetry.
Results Brown-adipose-tissue activity was observed in 23 of the 24 subjects (96%) during cold exposure but not under thermoneutral conditions. The activity was significantly lower in the overweight or obese subjects than in the lean subjects (P=0.007). BMI and percentage of body fat both had significant negative correlations with brown adipose tissue, whereas resting metabolic rate had a significant positive correlation.
The researchers concluded that the percentage of young men with brown adipose tissue is higher than previously thought, but its activity is lower in men who are overweight or obese. Brown adipose tissue could be metabolically important in men, and may make it a target for the treatment of obesity.
New England Journal of Medicine