# How many calories does the human body expend to create 1 pint of blood?

**URL:** <https://boards.straightdope.com/t/how-many-calories-does-the-human-body-expend-to-create-1-pint-of-blood/572152>\
**Category:** Factual Questions\
**Created:** [February 21, 2011, 10:24pm UTC](https://boards.straightdope.com/t/how-many-calories-does-the-human-body-expend-to-create-1-pint-of-blood/572152 "2011-02-21T22:24:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\
**Post date:** [February 21, 2011, 10:24pm UTC](https://boards.straightdope.com/t/how-many-calories-does-the-human-body-expend-to-create-1-pint-of-blood/572152/1 "2011-02-21T22:24:10Z")

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Title says it all. Assume this is production above and beyond normal, such as when giving blood. I didn’t want to google this because the issue might be confused with how many calories are _in_ a pint of blood, which is a different issue.

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**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\
**Post date:** [February 21, 2011, 10:54pm UTC](https://boards.straightdope.com/t/how-many-calories-does-the-human-body-expend-to-create-1-pint-of-blood/572152/2 "2011-02-21T22:54:13Z")

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About six hundred.

From [this thread](http://boards.straightdope.com/sdmb/showthread.php?t=293965):

> [@](#):
>
> Transfusion Medicine  
> Volume 11 Issue 5 Page 390 - October 2001  
> doi:10.1046/j.1365-3148.2001.00328-2.x  
> Six hundred reasons to donate blood
> 
> D. A. Redelmeier
> 
> I walked back from an economics lecture, passed an advertisement for a weight-loss clinic, and arrived at my appointment to donate blood. A thought came to mind: why does a rational economist ever donate blood? The activity takes time, requires planning, involves transportation, causes pain, and indirectly leads to lost personal productivity. Additionally, some risk of financial cost is assumed if sloppy application of the disinfectant causes a bad clothing stain.
> 
> I then had an idea. Perhaps blood donation could be promoted as one way to lose a bit of unwanted weight. Taking into account the composition and energy in each component (Rechcigl, 1978; Kratz et al., 1998), I estimated that one unit of blood reflects about 600 cal of food intake. Hence, a single donation can off-set either 2 hamburgers, 3 donuts, or 5 granola bars. Awareness of these statistics might increase the appeal of blood donation, particularly among healthy adults who are concerned about obesity.
> 
> References
> 
> • Rechcipl, M. [ed.] (1978) CRC Handbook Series in Nutrition and Food Section E Nutritional Disorders, Vol II. CRC Press Inc., p402.
> 
> • Kratz, A., Kent, B., Lewandrowski, K.B. (1998) Case Records of the Massachusetts General Hospital (Normal Reference Laboratory Values). New England Journal of Medicine, 339, 10631072.

ETA: Sorry, I now realize you wanted “expend to create” not “in”. Well, still interesting. Maybe?

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**Author:** ![wheresmymind](https://avatars.discourse-cdn.com/v4/letter/w/91b2a8/32.png) [@wheresmymind](https://boards.straightdope.com/u/wheresmymind)\
**Post date:** [February 21, 2011, 11:34pm UTC](https://boards.straightdope.com/t/how-many-calories-does-the-human-body-expend-to-create-1-pint-of-blood/572152/3 "2011-02-21T23:34:54Z")

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Although it varies quite a bit, a rule of thumb is that growth efficiency in most organisms is around 10%. If a pint of blood has about 600 calories, it would take _on the order of_ 6000 calories to produce it. This is a pretty rough estimate, but it looks like a pint of blood represents about 1-3 days of food intake.

I’d be very interested to know just how wrong or right I am.