Short-term Cold Acclimation Recruits Brown Adipose Tissue in Obese Humans.
Level 4 - case-series / case-control
Uncontrolled pre-post intervention study in a single small cohort
PubMed 26718499 · doi:10.2337/db15-1372
What was done
Ten metabolically healthy obese male subjects underwent a 10-day cold acclimation protocol. Brown adipose tissue (BAT) and white adipose tissue (WAT; visceral and subcutaneous) glucose uptake during cold exposure were assessed using [18F]fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT). Skeletal muscle biopsies were performed to examine basal sarcolemmal GLUT4 localization alongside muscle glucose uptake. Proximal skin temperature and subjective cold tolerance were also evaluated before and after acclimation.
What was found
The 10-day cold acclimation protocol resulted in an increase in cold-induced glucose uptake in BAT (no numerical values or effect sizes provided in the abstract). BAT activity was negatively correlated with age and trended negatively with body fat percentage. BAT glucose uptake was positively correlated with visceral WAT glucose uptake, although absolute glucose uptake within visceral and subcutaneous WAT depots did not change post-acclimation. Cold-induced skeletal muscle glucose uptake trended upward, paralleled by an increase in basal GLUT4 localization at the sarcolemma. Proximal skin temperature rose and subjective responses to cold showed slight improvement.
Why it matters
This study shows that BAT recruitment and skeletal muscle glucose-handling adaptations can be induced by short-term mild cold exposure even in obese individuals, suggesting potential therapeutic utility for metabolic conditioning.
Limits
The sample size is very small (n = 10) and exclusively comprised metabolically healthy obese men, limiting generalizability to females, older individuals, or patients with overt insulin resistance/type 2 diabetes. The study lacked an unexposed parallel control group, and the abstract omits quantitative effect sizes, variance measures, and exact p-values. Long-term persistence of metabolic changes after cessation of cold exposure was not evaluated.
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