The human brain uses about 25% of the human body's metabolic energy. How are the other 75% spent, in terms of portioning to its various systems?

I thought this could be answered by a simple search, but I can't find the answer after searching very hard. I only got dieting advices.

I am envisioning the best answer to look like

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    $\begingroup$ You presumably didnʼt find an easy answer because, unlike for the brain, the metabolic expenditure of other organs varies dramatically based on their need. In this context, basal rates are only so useful. $\endgroup$ Nov 25, 2019 at 20:11
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    $\begingroup$ Your vision of an answer seems to me more of a nightmare. This is an example of a representation that would be totally inappropriate to the question you ask. Why do you think that the different coloured items (energy/tissue?) need to be shown leading into something (Total) and what is the equivalent of the traces moving up or down or splitting? Sorry to sound severe, but there is a general problem that people do not think what graphical representations are appropriate for a particular data set. A pie chart will do, but the danger is thinking this is absolute, as @KonradRudolph points out. $\endgroup$
    – David
    Nov 26, 2019 at 17:57
  • $\begingroup$ Woah, 25% of the energy is lost to distribution? That's a lot. I cannot understand the other 29.52% because the graph is really messy there. $\endgroup$
    – WoJ
    Nov 27, 2019 at 13:58

1 Answer 1


Percent of basal metabolic rate by organ (BC Campus Open Education):

  • Liver and spleen : 27%
  • Brain: 19%
  • Skeletal muscle: 18%
  • Kidneys: 10%
  • Heart: 7%
  • Other tissues (lungs, intestine, skin, bone, fat tissue, glands...): 19%

Basal metabolic rate by organ

Basal metabolic rate by 1 kg of specific organ tissue (kcal/kg of organ/day) (Table 5 from American Journal of Clinical Nutrition, 2010):

  • Heart: 440 kcal/kg
  • Kidneys: 440 kcal/kg
  • Brain: 240 kcal/kg
  • Liver: 200 kcal/kg
  • Skeletal muscle: 13 kcal/kg
  • Adipose tissue: 4.5 kcal/kg
  • Residual tissues (lungs, intestine, skin, bone...): 12 kcal/kg
  • $\begingroup$ Why are liver and spleen aggregated? $\endgroup$ Nov 26, 2019 at 13:50
  • $\begingroup$ @MJD, It's them (BC Campus) that merged them, not me. "Liver and spleen" are often mentioned together because they share some functions. $\endgroup$
    – Jan
    Nov 26, 2019 at 13:52
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    $\begingroup$ Where is the stomach and intestines? They utilize so much energy in the digestion process. $\endgroup$
    – Loren
    Nov 27, 2019 at 18:22
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    $\begingroup$ @Loren, stomach and intestine are active only during digestion, while the heart, kidneys and liver work all the time...I mentioned intestine under "other tissues" - I'll see if I can find some more specific data. $\endgroup$
    – Jan
    Nov 28, 2019 at 14:40
  • $\begingroup$ Based on the per-weight list (and this paper), if we separated the liver from the spleen, the liver would represent ~17%, lower than the brain. $\endgroup$ Oct 2, 2022 at 18:19

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