Cold plunges for fat loss — does the science back it up?
Cold plunges and ice baths claim to burn fat by activating brown fat. But does shivering in the cold actually melt meaningful weight, or is it mostly hype?
- Claim
- COLD PLUNGES BURN FAT?
- Catch
- TINY EFFECT
- Verdict
- NOT A FAT-LOSS HACK
A 2009 NEJM study put 24 men at 16°C for two hours. Lean men had active brown fat; overweight men barely did. Cold raised energy expenditure by about 80 calories a day — a 5 percent bump.
A 2011 trial had men sit at 19°C for two hours daily, six weeks straight. Brown fat activity rose 40 percent. Energy expenditure during cold jumped 250 calories. They lost 1.5 kilos of body fat — but only during those cold hours.
The catch: that 250 calories only happens while you're cold. Most of the initial burn is shivering — muscle contractions, not brown fat. Brown fat takes weeks of daily cold to recruit. And 250 calories is two cookies, not a weight-loss strategy.
SOURCES
- van Marken Lichtenbelt WD, et al. Cold-Activated Brown Adipose Tissue in Healthy Men. N Engl J Med. 2009;360(15):1500-1508. doi:10.1056/NEJMoa0808718
- Yoneshiro T, et al. Recruited brown adipose tissue as an antiobesity agent in humans. J Clin Invest. 2011;121(7):2962-2969. doi:10.1172/JCI46275
- Lee P, et al. Temperature-acclimated brown adipose tissue modulates insulin sensitivity in humans. Cell Metab. 2014;19(2):302-309. doi:10.1016/j.cmet.2014.01.007
For information only, not medical advice. Talk to a doctor before extreme cold exposure.
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