It's common knowledge that shivering in the
cold is part of the body's attempt to stay warm.
According to new research into the
mechanisms involved, shivering releases a hormone that stimulates fat tissue to
produce heat so that the body can maintain its core temperature. This hormone,
irisin, is also produced by muscle during exercise.
The findings, which are published in the
February issue of the Cell Press journal Cell Metabolism, demonstrate that the
act of shivering produces calorie-burning brown fat and improves metabolism.
Through experiments conducted in healthy
volunteers, Dr Francesco S Celi of the National Institute of Diabetes and
Digestive and Kidney Diseases and his colleagues found that the irisin,
produced when the body shivers, is released in proportion to shivering
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Furthermore, the amount of irisin secreted
as a result of shivering is of similar magnitude to that of exercise-stimulated
The team also found that when human fat
cells in the laboratory were treated with FNDC5, a precursor of irisin, the
cells burned more energy and released more heat.
Lowering the thermostat
The results suggest that exercise-induced
production of irisin could have evolved from a similar mechanism that occurs
following shivering-related muscle contractions in order to burn calories and
"This research may reveal why exercise
increases secretion of a hormone that makes the body maintain its internal
temperature," said Dr Celi, who is currently at Virginia Commonwealth
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This may help explain why exercise increases
secretion of a hormone that, paradoxically, makes the body feel hotter.
The findings also suggest that exploiting
the muscle-fat crosstalk that is mediated by irisin may represent a new
strategy to treat or prevent obesity.
The results may even help people embrace
feeling cold. "Perhaps lowering the thermostat during the winter months
could help both the budget and metabolism," said Dr Celi.
Picture: Shivering from Shutterstock
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