Episode 14 – Freezing your fat off

Show notes:

  • Study è “Short-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitus” (Hanssen et al. 2015)
  • Brown adipose tissue (BAT) was ‘rediscovered’ in 2009
  • Cold exposure increases BAT & its activity
  • BAT activity was determined by measured glucose uptake via 18FDG PET-CT
  • Data suggests BAT activation correlates with decreased triglycerides in BAT tissue
  • More glucose was taken up (on average) in skeletal muscle & BAT tissue post-cold adaptation
  • Uncoupling potein-1 (UCP-1) expressing white adipose tissue (WAT), like visceral and subcutaneous fat, didn’t take up more glucose after acute cold exposure
  • After acute cold exposure, only supraclavicular differences in BAT activity was seen (not in other tissues)
  • There is shivering thermogenesis and Non-shivering thermogenesis (NST)
  • Insulin sensitivity (IS) (via hyperinsulinemic-euglycemic clamp) improved 43% on average post-cold adaptation. This is more than seen in long-term endurance exercise!
  • IS improvements come from increased peripheral glucose disposal
  • Non-esterified fatty acids (NEFAs) were lower during clamp post-cold adaptation, suggesting increased adipose tissue IS
  • In skeletal muscle post-cold adaptation, GLUT1 protein levels stayed the same but GLUT4 increased x10
    • GLUT1 = ubiquitous (apparently more dense in muscle & capillaries according to new studies) but mostly on red blood cells (erythrocytes) according to textbook, specific to D-glucose and works on basal uptake (according to concentration) in a non-insulin dependent manner
    • GLUT4 = found in muscle, fat tissue and the heart, it’s activity is insulin dependent
  • Meeting abstract è Cold acclimation and health: effect on brown fat, energetics, and insulin sensitivity (Lichtenbelt et al. 2015)

Study testing the breathing technique (re)pioneered by Wim Hof in 12 control and 12 trained subjects è Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans (Kox et al. 2014)

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