# Can BMI results be skewed by really large breasts? **URL:** \ **Category:** Factual Questions\ **Created:** [September 11, 2017, 5:48pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071 "2017-09-11T17:48:29Z")\ **Posts on this page:** 16\ **Page:** 2
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [September 12, 2017, 12:57pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/21 "2017-09-12T12:57:53Z")
> [@Joey\_P](#): > > [R.O.U.S.](https://www.youtube.com/watch?v=BOv5ZjAOpC8)es are from The Princess Bride. They’re giant rats. > > The clip is safe for work (and everyone has seen it), but it could be a bit loud so watch your sound (but keep the sound on, the phrase ‘ROUS’ is used at the very beginning). Only the \*\*\*BEST \*\*\*movie ever. (I wish there was more I could do to emphasize how \*\*\*BEST \*\*\*it is.) FTR, (and speaking as an amateur, not a professional comic) I always felt R.O.U.S. part was “flubbed”. I don’t think the ROUS should have been revealed to the audience until it leaped out at Wesley and Buttercup. On subject, even if the mass of breastage significantly affected BMI, the next question would be whether this specific fat affects health the same as fat in other areas or not. (This is, of course, ignoring issues of back strain, etc and also ignoring the potential effects of a (possibly factitiously) elevated BMI score. ---
**Author:** ![Hilarity\_N.Suze](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hilarity_n.suze/32/6223_2.png) [@Hilarity\_N.Suze](https://boards.straightdope.com/u/Hilarity_N.Suze)\ **Post date:** [September 12, 2017, 5:05pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/22 "2017-09-12T17:05:43Z")
I think, if what you’re measuring is fat percentage overall, it does count. But probably not a lot for BMI. When they use the calipers, they use them on your arms and midsection if I’m remembering right. So for that measurement, fat in breast tissue wouldn’t necessarily count against you. When they do the thing where you grasp this little electrical dealie, I do think it counts for the total body fat, but it’s not as bad to have it there as to have it in your abdomen. ---
**Author:** ![Atamasama](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/atamasama/32/12961_2.png) [@Atamasama](https://boards.straightdope.com/u/Atamasama)\ **Post date:** [September 12, 2017, 5:41pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/23 "2017-09-12T17:41:51Z")
> [@Hilarity\_N.Suze](#): > > I will say this about BOUS though. Back in the days before BMI was the thing, you used to hear, “Stand up straight with your back to a wall. Look down. If you can’t see your feet, you are fat.” > > Well, I couldn’t see my feet. It always made me feel like the fattest 100-lb. woman ever. Those guys with huge guts and clown feet are content with their fitness levels. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [September 12, 2017, 7:40pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/24 "2017-09-12T19:40:06Z")
> [@Hilarity\_N.Suze](#): > > I think, if what you’re measuring is fat percentage overall, it does count. But probably not a lot for BMI. > > When they use the calipers, they use them on your arms and midsection if I’m remembering right. So for that measurement, fat in breast tissue wouldn’t necessarily count against you. When they do the thing where you grasp this little electrical dealie, I do think it counts for the total body fat, but it’s not as bad to have it there as to have it in your abdomen. Well, yes, it counts in those measures. But maybe it shouldn’t. Maybe the fat content of large breasts doesn’t independently correlate with cardiovascular risk or risk if metabolic syndrome. Fortunately, it looks like any skew effect may be small, even for BOUS. Still… maybe an NIH funded study is in order. It would be quite the Doper coup for a bunch of us to visit stripper bars (and other Dems of iniquity) on the taxpayer’ dime. 🙂 ---
**Author:** ![dba\_Fred](https://avatars.discourse-cdn.com/v4/letter/d/c37758/32.png) [@dba\_Fred](https://boards.straightdope.com/u/dba_Fred)\ **Post date:** [September 12, 2017, 10:59pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/25 "2017-09-12T22:59:27Z")
“ **Dems** of iniquity?” We call the study _The Wilbur Mills Memorial (D-Ark) Fanny Foxe BOUS Survey_. (ya know who else was from Arkansas?) ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [September 12, 2017, 11:13pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/26 "2017-09-12T23:13:10Z")
> [@dba\_Fred](#): > > “ **Dems** of iniquity?” > > We call the study _The Wilbur Mills Memorial (D-Ark) Fanny Foxe BOUS Survey_. > > (ya know who else was from Arkansas?) Darn autocorrect! ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [September 13, 2017, 1:10am UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/27 "2017-09-13T01:10:38Z")
> [@Blue\_Blistering\_Barnacle](#): > > Still… maybe an NIH funded study is in order. It would be quite the Doper coup for a bunch of us to visit stripper bars (and other Dems of iniquity) on the taxpayer’ dime. 🙂 Too many, shall we say, false[sup]1[/sup] positives in such places. Those would skew the results. [sup]1[/sup] False as in artificially enhanced, of course. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [September 13, 2017, 7:05am UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/28 "2017-09-13T07:05:39Z")
I’ll just note that there are women who use saline injections to increase their bust size to pumpkin contest winning sizes and I think it’s fair to expect that adding 40-60 pounds of water weight is going to noticeably affect your BMI. While useful at a population level, BMI is only well correlated to anything medically noteworthy in the case of “average” people. As should be obvious, chopping of your leg may take you into the “safe” zone of BMI, but it don’t change your risks of diabetes. If you are non-normal in some way, then your body fat percentage is the only useful metric. On the plus side, it’s usually going to be fairly obvious to anyone reasonable whether the BMI will suffice for a particular person. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [September 13, 2017, 12:47pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/29 "2017-09-13T12:47:11Z")
> [@Sage\_Rat](#): > > I’ll just note that there are women who use saline injections to increase their bust size to pumpkin contest winning sizes and I think it’s fair to expect that adding 40-60 pounds of water weight is going to noticeably affect your BMI. > > While useful at a population level, BMI is only well correlated to anything medically noteworthy in the case of “average” people. As should be obvious, chopping of your leg may take you into the “safe” zone of BMI, but it don’t change your risks of diabetes. If you are non-normal in some way, then your body fat percentage is the only useful metric. **On the plus side, it’s usually going to be fairly obvious to anyone reasonable whether the BMI will suffice for a particular person**. _My bolding in quote._ You’d like to think so. What happens is, a researcher notices a correlation. They work it up, maybe refine the parameters and add qualifications, frequently stating something like, “this is good for population studies only” or somesuch. Then it gets rolled out for general use, where it may be initially applied correctly. As it gains wider acceptance, it becomes more and more misapplied, and is eventually built into computer algorithms, which resist correction or circumvention. Then “That’s the way it is! Your BMI sucks!”. Then you look at the calendar, and “Whoa, it’s 2017!” ---
**Author:** ![shiftless](https://avatars.discourse-cdn.com/v4/letter/s/e9c0ed/32.png) [@shiftless](https://boards.straightdope.com/u/shiftless)\ **Post date:** [September 13, 2017, 3:52pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/30 "2017-09-13T15:52:28Z")
BMI is at best a very rough estimate of body fat. It’s not a bad place to start because it’s so much easier to calculate than any other fat/lean measurement, but it can’t be taken too seriously. The BMI charts do not account for body shape. At the end of the day, a person with large breasts is going to be carrying a higher percentage of body fat than a person with small or no breasts, simply because breasts don’t count as lean. A short, muscular person can easily fall into the obese range. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [September 14, 2017, 4:35pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/31 "2017-09-14T16:35:01Z")
> [@LSLGuy](#): > > Wiki [Breast - Wikipedia](https://en.wikipedia.org/wiki/Breast#Anatomy) sez a small breast is around a half-pound whereas a huge one is implied to be 3ish lbs. So that’s a 3 lb swing from small to huge. Times 2 breasts = 6 lbs. … That seems likely to be correct but not sure if GQ here should be satisfied with a Wikipedia article that has no primary source attached to the factoid as adequate for declaring what “really large breasts” can weigh. Another unsourced citation, [LiveScience](https://www.livescience.com/32397-what-is-the-average-american-womans-bust-size-.html), claims that > [@](#): > > Bras must support a pair of breasts that can weigh just over a half pound (0.3 kilograms) to a whopping 20 pounds (9 kilograms). Who is right? We have particular no reason to believe the 20 pound … figure … either, or if that only occurs in someone who is otherwise morbidly obese. In any case the precise question of the op is easily answered even if the answer is trivial: the (of very limited individual value) _definition_ of “overweight” by BMI is a precise number, 25 to 29.9, and therefore a … swing … of the wiki deduced 1 BMI point, if that is what it is from the impact of small to large breasted on BMI, would without question move any woman who would be 24 to 24.9 if small breasted to the “overweight” classification if they were large breasted. And that is not allowing for any secondary impact of the larger breasts on core muscle mass. As has been covered here often, BMI is a great tool to study populations as wholes, and a reasonable _screening_ instrument for individuals, but it is of limited utility for individuals, especially in the “overweight” classification range. Those whose BMIs classify them as “obese” are OTOH extremely likely also be considered to have excess adiposity by almost any other measurement or classification technique. ---
**Author:** ![Spiderman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spiderman/32/230_2.png) [@Spiderman](https://boards.straightdope.com/u/Spiderman)\ **Post date:** [September 14, 2017, 5:15pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/32 "2017-09-14T17:15:57Z")
> [@dba\_Fred](#): > > note to self: buy wife size 10 jeans, observe 🙂 > > next note to self: first find a wife If I may be so bold, allow me to set you up with your new [wife](http://2.bp.blogspot.com/-E2EMDSX2i1Y/TubOzrleAhI/AAAAAAAAFns/t0r3nxy7QeI/w1200-h630-p-k-no-nu/1098_PanicPete_1B.jpg). ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [September 14, 2017, 5:30pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/33 "2017-09-14T17:30:19Z")
> [@DSeid](#): > > Another unsourced citation, [LiveScience](https://www.livescience.com/32397-what-is-the-average-american-womans-bust-size-.html), claims that Who is right? We have particular no reason to believe the 20 pound … figure … either, or if that only occurs in someone who is otherwise morbidly obese. Well, we can tackle this with math. According to the University of Google, fat is around 0.9 grams per cc. So slightly less dense than water. A gallon of water weighs 8.34 pounds. So a good back-of-the-envelope estimate for breast weight is around 8 pounds for every gallon milk/water jug volume of…well…jug. You can do mental estimates comparing breasts to 1-gallon containers. The first person who comes to mind with especially large breasts (famous for having them reduced) is Soleil Moon Frye. [Looking at photos](https://www.google.com/search?biw=1056&bih=518&tbm=isch&sa=1&q=soleil+moon+frye+pre-surgery&oq=soleil+moon+frye+pre-surgery&gs_l=psy-ab.3...5522.8630.0.8917.12.7.0.0.0.0.0.0..0.0....0...1.1.64.psy-ab..12.0.0....0.KbCHYppw8r0) is it possible that together her pre-op breasts were as large as 2.5 gallons of water? Just as a naked-eye (and clothed breast!) estimate, that doesn’t seem too far off. And she otherwise had a pretty normal figure. So it seems that 20 pounds may be on the upper end of the natural bell curve. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [September 14, 2017, 5:42pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/34 "2017-09-14T17:42:35Z")
> [@shiftless](#): > > A short, muscular person can easily fall into the obese range. My goal has always been to have a BMI that puts me in the “Obese” category. Right now, I’m only “Overweight” (BMI 25.4, with body fat percentage of 17.1). ---
**Author:** ![Weisshund](https://avatars.discourse-cdn.com/v4/letter/w/ba8739/32.png) [@Weisshund](https://boards.straightdope.com/u/Weisshund)\ **Post date:** [September 14, 2017, 8:02pm UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/35 "2017-09-14T20:02:04Z")
> [@RivkahChaya](#): > > Anyway, if big boobs that were not the result of implants did throw off a BMI, I’m pretty sure mine would. And they don’t. They are, however, the reason I wear size 10 jeans and XL shirts. With out sounding odd, could you explain that? The pants part? Exactly where are you wearing the pants? ---
**Author:** ![Atamasama](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/atamasama/32/12961_2.png) [@Atamasama](https://boards.straightdope.com/u/Atamasama)\ **Post date:** [September 15, 2017, 12:30am UTC](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071/36 "2017-09-15T00:30:30Z")
> [@Weisshund](#): > > With out sounding odd, could you explain that? > The pants part? > Exactly where are you wearing the pants? If I may be so bold as to offer a plausible explanation, I believe the implication is that size 10 jeans fit on a slender woman not expected to have to wear an XL shirt; however a large bust size makes it necessary to wear such a shirt despite being slim otherwise. [Previous page](https://boards.straightdope.com/t/can-bmi-results-be-skewed-by-really-large-breasts/796071.md?page=1)