Effect of prolonged, mild cold exposure on metabolic regulation in insulin resistant overweight and obese men

Abstract

The purpose of this study was to investigate the effect of prolonged, mild cold exposure (CE) on metabolic regulation in middle‐aged and older, overweight and obese males. Eight men (51.9 ± 4.4 years old, BMI 29.7 ± 1.4 kg/m2) completed two trials: a) 8 h CE (17 – 19°C) above the shivering threshold and b) 8 h in thermoneutral (TN) conditions (26 – 28 °C). In the final two hours of each trial, hyperinsulinemic euglycemic clamps were performed to determine insulin sensitivity. Insulin sensitivity was higher after CE compared with TN conditions (1.5 ± 0.3 *10−3 dL−1.kg−1.min−1 vs 1.0 ± 0.2*10−3 dL−1.kg−1.min−1, p=0.02). Mild CE decreased skin (31.1 ± 1.1 °C vs 34.5 ± 0.3 °C, p < 0.001), but not core temperatures (36.5 ± 0.3 °C vs 36.8 ± 0.6 °C) compared with TN conditions. Next day fasting plasma triglycerides and VLDL‐cholesterol were lower after the CE trial compared with TN (164 ± 17 mg.dl−1 vs 197 ± 22 mg.dl−1, p = 0.02 and 33±4 mg.dl−1 vs 39.3 ± 4.4 mg.dl−1, p = 0.01, respectively). Prolonged, mild CE improves the metabolic profile of insulin resistant obese men. Future studies will determine if these findings are mediated via activation of brown adipose tissue, as it has recently been suggested that CE activates brown adipose tissue in many humans. Research Support: CTSA UL1TR000071, Pepper Center Pilot Grant, Sealy Center on Aging, Shriners Hospitals for Children Grant 84090, Onassis Foundation