# How many calories/day does it take to grow your beard? **URL:** \ **Category:** Factual Questions\ **Created:** [March 27, 2008, 3:47am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886 "2008-03-27T03:47:36Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Nunavut\_Boy](https://avatars.discourse-cdn.com/v4/letter/n/e95f7d/32.png) [@Nunavut\_Boy](https://boards.straightdope.com/u/Nunavut_Boy)\ **Post date:** [March 27, 2008, 3:47am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/1 "2008-03-27T03:47:36Z")
Can’t find anything with google and I don’t have a calorimeter. What say you? ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [March 27, 2008, 4:39am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/2 "2008-03-27T04:39:55Z")
Why not ask the folks over on the [Beard Board](http://www.beardboard.net/)? ---
**Author:** ![Nunavut\_Boy](https://avatars.discourse-cdn.com/v4/letter/n/e95f7d/32.png) [@Nunavut\_Boy](https://boards.straightdope.com/u/Nunavut_Boy)\ **Post date:** [March 28, 2008, 12:23am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/3 "2008-03-28T00:23:29Z")
Bump. No one’s even going to offer a WAG? ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [March 28, 2008, 3:19am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/4 "2008-03-28T03:19:41Z")
> [@](#): > > Hair growth varies depending on body region. For example, average eyelash/brow growth rates have been reported at 0.16 millimeters (mm) per day, scalp hair at 0.34 to 0.36 mm/day, and beard hair at 0.38 mm/day. > **[ATSDR Hair Analysis Panel Discussion: Section 2.4](https://www.atsdr.cdc.gov/hac/hair_analysis/2.4.html)** > > Hair Analysis: Use of hair analysis in assessing environmental exposures. > [@](#): > > Did you know that the average human face contains 615 hairs per square centimeter? > **[Directnic Parking](http://www.shavingstuff.com/archives/2004_12.php)** > [@](#): > > if you have a very thick beard, you can roughly estimate the total area of beard coverage is approximately 1/5th of the total area of scalp hair coverage. [http://www.baldingblog.com/2007/07/12/how-many-hairs-does-a-man-lose-from-his-beard-each-day/](http://www.baldingblog.com/2007/07/12/how-many-hairs-does-a-man-lose-from-his-beard-each-day/) > [@](#): > > It is interesting to know that the total amount of scalp in the human being is 400 square centimeters (160 square inches). [http://www.calvicieadios.com/ingles/paginas/information.htm](http://www.calvicieadios.com/ingles/paginas/information.htm) A thick beard of 80 square centimeters extent will thus have about 49,200 hairs. If each of those hairs grows 0.38 mm a day, the total growth of hair shaft is 18.7 meters per day. > [@](#): > > For an average human beard hair, having a diameter of about 100 μm [http://www.wipo.int/pctdb/en/wo.jsp?IA=WO2007039854&DISPLAY=DESC](http://www.wipo.int/pctdb/en/wo.jsp?IA=WO2007039854&DISPLAY=DESC) But it’s usually [triangular](http://cienciaforense.com/Pages/PhysicalEvidence/HairInvestigation.htm) . I’ll ignore that, and treat it as a circle. 18.7 meters of beard hair will thus have a volume of 0.0367 cubic centimeters (36.7 microliters). Hair is mostly protein, so the question becomes “How much energy does it take to produce 0.0367 cubic centimeters of protein?” Proteins typically have a density of around [1.35 g/cm^3](http://www.proteinscience.org/cgi/content/full/13/10/2825) So that 0.0367 cubic centimeters will mass about 0.05 grams. There is no average figure for the energy requirement of protein synthesis. The number depends on the amino acid composition of the protein, as well as the diet and hormonal status of the individual making the protein. That being the case, I’ll just drag in a number from a [dietary study in sheep](http://jas.fass.org/cgi/reprint/38/2/378.pdf) (pdf): > [@](#): > > Protein synthesis required 45.6 -+ 8.69 kcal metabolizable energy (ME) per gram If men are like sheep, it’ll take 2.28 kcal to grow a days worth of beard. That’s not much. ---
**Author:** ![Bob55](https://avatars.discourse-cdn.com/v4/letter/b/e9c0ed/32.png) [@Bob55](https://boards.straightdope.com/u/Bob55)\ **Post date:** [March 28, 2008, 3:22am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/5 "2008-03-28T03:22:41Z")
Well, considering the basal metabolic rate for most men is around 1500-2000 calories a day, I’ll say that growing a beard only sucks away about 1 to 5 calories of that. Considering a man produces 200,000,000 sperm a day, I doubt producing some cell divisions on our face is all that consuming. I tried to do the math but it would take a bit of work and it’s late, but basically you need to find out how much ATP is used per cell division, and how many cell divisions a day are performed per hair cell, and multiply that by the number of hairs on your face. ATP produces 7.3 kcal (Calories) per mole, but in the cell due to concentration gradients that is actually up around 12 kcal/mole. I know that you use half of your body weight of ATP a day, or about 150 moles of ATP (or 150 x 6.02x10^23 molecules). So, assuming all 2000 calories is converted to the 150 moles of ATP, and assuming ~10 trillion cells in your body, each cell, that gives each cell 9.03x10^12 ATP to use per day. Of course, dividing cells use more ATP than non-dividing cells, and that is probably not possible to determine. Ok, easier way - assuming 2000 calories, that gives each cell 2x10^-10 calories to use (2000 / 10 trillion). So, how many cells are in a hair follicle, and how many hairs are on your face? I’m beginning to think it might be less than a calorie. ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [March 28, 2008, 3:39am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/6 "2008-03-28T03:39:26Z")
[QUOTE=Squink] \ If men are like sheep, it’ll take 2.28 kcal to grow a days worth of beard. That’s not much. [/QUOTE] 1 kcal = 1 “regular” calorie, correct? so I probably breath in this much caloric dust in a day, and it’s probably equivalent to licking a postage stamp? ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [March 28, 2008, 5:08am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/7 "2008-03-28T05:08:01Z")
You actually burn \*\*\*fewer \*\*\*calories by growing a beard: First of all, you don’t burn any \*\*\*extra \*\*\*calories. Your facial hair doesn’t grow at a different speed, depending on whether you shave. The number of calories your hair follicles burn remains the same. BUT . . . The act of shaving burns a certain number of calories, so if you stop shaving, those calories are not burned. ---
**Author:** ![Two\_and\_a\_Half\_Inches\_of\_Fun](https://avatars.discourse-cdn.com/v4/letter/t/ea666f/32.png) [@Two\_and\_a\_Half\_Inches\_of\_Fun](https://boards.straightdope.com/u/Two_and_a_Half_Inches_of_Fun)\ **Post date:** [March 28, 2008, 5:10am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/8 "2008-03-28T05:10:13Z")
[QUOTE=panache45] You actually burn \*\*\*fewer \*\*\*calories by growing a beard: First of all, you don’t burn any \*\*\*extra \*\*\*calories. Your facial hair doesn’t grow at a different speed, depending on whether you shave. The number of calories your hair follicles burn remains the same. BUT . . . The act of shaving burns a certain number of calories, so if you stop shaving, those calories are not burned. [/QUOTE] But you have to carry around the extra weight of the beard. ---
**Author:** ![IAmNotSpartacus](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@IAmNotSpartacus](https://boards.straightdope.com/u/IAmNotSpartacus)\ **Post date:** [March 28, 2008, 6:02am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/9 "2008-03-28T06:02:26Z")
[QUOTE=Two and a Half Inches of Fun] But you have to carry around the extra weight of the beard. [/QUOTE] Also don’t forget the increase in energy it will take to move around due to the drag the beard creates. ---
**Author:** ![Nunavut\_Boy](https://avatars.discourse-cdn.com/v4/letter/n/e95f7d/32.png) [@Nunavut\_Boy](https://boards.straightdope.com/u/Nunavut_Boy)\ **Post date:** [March 28, 2008, 11:47am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/10 "2008-03-28T11:47:34Z")
Huh. Thanks for that, guys. I would’ve thought it was a bit more. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [March 28, 2008, 12:29pm UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/11 "2008-03-28T12:29:05Z")
[QUOTE=Two and a Half Inches of Fun] But you have to carry around the extra weight of the beard. [/QUOTE] Plus the fact that your wallet will be heavier, with the money you would have spent on razors and shaving cream. ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [March 28, 2008, 12:33pm UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/12 "2008-03-28T12:33:46Z")
I’ve been dead for three days and my beard is _still_ growing. ---
**Author:** ![Cluricaun](https://avatars.discourse-cdn.com/v4/letter/c/bb73d2/32.png) [@Cluricaun](https://boards.straightdope.com/u/Cluricaun)\ **Post date:** [March 28, 2008, 2:08pm UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/13 "2008-03-28T14:08:16Z")
Let’s not forget the calories that you lose due to food getting stuck in your beard on the way into your mouth. Seriously though, threads like this one remind me again why I love this place. **Squink** , that was awesome. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 28, 2008, 2:15pm UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/14 "2008-03-28T14:15:54Z")
[QUOTE=Cluricaun] Let’s not forget the calories that you lose due to food getting stuck in your beard on the way into your mouth. [/QUOTE] Not to worry - You can always pick it out and eat it later, if you feel yourself flagging. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [March 28, 2008, 2:21pm UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/15 "2008-03-28T14:21:06Z")
How do the calories spent shaving compare to the calories spent trimming a beard and running your fingers through it? ---
**Author:** ![Melkor28](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Melkor28](https://boards.straightdope.com/u/Melkor28)\ **Post date:** [March 30, 2008, 10:51am UTC](https://boards.straightdope.com/t/how-many-calories-day-does-it-take-to-grow-your-beard/442886/16 "2008-03-30T10:51:55Z")
I was waching _The Humane Body_ on the Discovery Channel last week, about starvation. Under a certain calorie intake per day, all hair growth shuts down. I don’t remember the exact number, but about 1,000. ``` This guy survived 36 days ( If I remember correct), in a cave; no food, only mimimal water. ```