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I think that this question is on topic for this site as it states human physiology and pathophysiology is allowed. If not then please let me know in the comments and I shall delete this Question. Please let me know where this question would be better suited if possible.

A google for an answer to this mainly comes up with answers to why we shiver, and not to how much we heat up and what the different factors that affect this are. For instance does height, weight, and/or body fat percentage affect this? How much energy do we use to shiver and does it burn fat?

I'm asking in relation to when we shiver randomly, quickly, not continuously, as well as when we are cold and when we our body goes under rapid change in temperature (i.e an emergency blood transfusion with cold blood).

Reflexive
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    This is a complex question because of the term "heat up". At the most extreme end of shivering, before someone dies from hypothermia, the person feels extremely hot and often takes their clothes off; that's why people locked in freezers are often found dead and unclothed. – Snack_Food_Termite Jul 03 '19 at 03:36

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During shivering, the heat production in your body can be up to 3 times as high as in rest.

For comparison, during maximal exercise, the heat production can be up to 15-20 times as high as in rest.

So, practically speaking, shivering alone can prevent you from hypothermia only in relatively mild cold; to produce more heat you would need to do some voluntary muscular work, for example, by brisk walking or running.

By shivering, you burn calories from "brown fat" (more details on Physiology.org). Body fat, which is mostly "white fat," is a good insulator, so people with more fat may retain more heat produced by shivering than the skinny ones.

Another type of "cold-induced heat production" in your body is "nonshivering thermogenesis," which varies from 0 to 14% of resting metabolic rate in studies that last one to several days and up to 30% in short-term (hours) studies (Physiology.org).

The main source of this answer: Shivering thermogenesis in humans: Origin, contribution and metabolic requirement (Tandofline, 2017)

Jan
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  • Thanks, I suppose it would be too hard to calculate how much you heat up, but I suppose this is as close an answer as ill get. Thanks. – Reflexive Jul 04 '19 at 12:59
  • @Reflexive, I can try to calculate it, but it would help me if you say how can this help you. – Jan Jul 04 '19 at 13:52
  • This question was more to fuel my own curiosity. Was it wrong of me to ask that kind of question here? – Reflexive Jul 04 '19 at 14:01
  • @Reflexive, it's OK. I believe I made my answer a bit more useful. There are also a lot of details in the linked articles. – Jan Jul 04 '19 at 15:11
  • Thanks! I'm reading through that article (shivering thermogenisis in humans), and I think this is exactly what I was looking for! – Reflexive Jul 04 '19 at 15:37