Talk:Body mass index

message: I've created a new BMI chart that I'd like to add to the article. My aim was to make it easier to read, and since our readers may come here to do just that I have a suggestion; Rather than simply swapping out the infobox image I'd like to place the new BMI chart in the article as a , as shown below. So to avoid duplication I suggest that :File:Obesity & BMI.png be moved to the infobox.
I was going to boldly edit the article myself but, since it's quite a drastic change, I thought I should mention it here first. nagualdesign 19:09, 3 June 2021 (UTC)
replies: text: Having made the edit a few hours ago, looked at it on desktop and on mobile, then thought about it for a while, I changed my mind. The  looks okay on a desktop browser and it's kind of readable on mobile but being so far down the page lacked prominence, particularly on mobile where you had to scroll quite a way to even see it. What I was trying to do was avoid having to click through in order to read the chart but, for readers who come here specifically looking for a chart, having to click on it (in the infobox) is far simpler than having to scroll down to even find it. Plus, the infobox image will show up on Google search results so the chart is more appropriate. In the end I've essentially just swapped the old chart for the new one. nagualdesign 23:18, 3 June 2021 (UTC)
thread_title:  Updated chart 

message: In the "Categories" section's BMI table, should the "BMI Prime" column be removed? Technically it is an alternative to BMI listed in the "Alternatives" section, which I don't think the WHO mentions in their study report. I'm not even sure if it is widely used or popular. The WHO does further divide some of the BMI categories, which could replace that column. Jroberson108 (talk) 14:32, 12 July 2021 (UTC)
thread_title:  BMI table's BMI Prime 

message: BMI categories are defined by ranges of numbers per this reliable source (The SuRF Report 2, p. 22), which uses two decimal precision (e.g. Overweight: 25.00-29.99; Obese I: 30.00-34.99). Some feel "29.999", etc. are "gaps" unaccounted for that can cause confusion and feel it unscientific and want to include all numbers by rounding the upper limits/boundaries (25-30; 30-35) implying ranges that exclude the upper limit (30 and 35 respectively) and barely "touch" the next category's lower limit. Others feel worrying about "29.99X" unnecessary, MOS:RANGE includes the upper limit, "30" in two categories is inaccurate and a confusing "overlap", and we should stick to WP:RS with one decimal precision being clear enough (25.0-29.9; 30.0-34.9). The latter is presently on the article page (see Categories) along with explanatory footnotes (efn) with text of "After rounding." added to each BMI table in their column headers to accommodate "gap" concerns. The opinions have not budged after discussion. Jroberson108 (talk) 23:26, 2 August 2021 (UTC)
replies: text: You really think that's neutrally worded? As has already been pointed out, there are many reliable sources, some of which use "18.5 to 25" while others use "18.5 to 24.99", etc. and we can cherry pick our sources for the article. Cherry picking one source for an RfC that suits your preference is a bit cheeky. Please can we just follow established procedures, explaining our personal preferences without POV pushing, otherwise it's all rather tedious. Cheers. nagualdesign 00:32, 3 August 2021 (UTC)
replies: text:  Not one other RS was provided, so I referenced the only one we have, which is used on the article. You refer to a hypothetical comment that the same editor denounced as not needed in this case, as I responded to you on the 26th, which you never responded to. You should read the discussion thoroughly. Chill out, we have already discussed everything we could and it isn't changing our opinions. Now let other editors give their opinions, which any one of them can and should read the entire discussion. It's just a summary of major content concerns. Jroberson108 (talk) 00:54, 3 August 2021 (UTC)

text: This nit simply not worth picking. BMI levels are not scientific concepts, they're general guidelines, and controversial ones at that. Nor is it practical to even calculate BMI to more than one decimal point. Let it go. — Isaac Rabinovitch (talk) 03:42, 3 August 2021 (UTC)
replies: text: The proposer conveniently forgets to mention that a version with only round boundaries like 25,30, 35 has been in the article for more than 10 years with very occasional exceptions and that he is the one who recently changed it. It must be clear that everyone agrees that the real boundaries between categories are these round numbers. The discussion is about how to represent this towards the reader as clearly as possible.−Woodstone (talk) 13:07, 3 August 2021 (UTC)
replies: text:  The history of edits was ignored since it is irrelevant when discussing actual content. Jroberson108 (talk) 19:50, 8 August 2021 (UTC)

text:   Thank you for taking the time to comment. I agree that we don't need to worry about "29.9X" and one decimal precision is practical enough. BMI guidelines do seem unscientific and controversial as you say. Jroberson108 (talk) 19:50, 8 August 2021 (UTC)
replies: text: That is the point. The category boundaries are rough and round numbers like 25, 30 etc. Therefore it makes no sense to burden the table with numbers such as 24.9 and 29.9, which are not category boundaries, because clearly 24.95 is still not meant to be seen as overweight. −Woodstone (talk) 13:13, 9 August 2021 (UTC)
replies: text:  The point is that you don't need to worry about "24.95" or any further precision, which it appears four editors (myself included) now agree is unnecessary and that one decimal precision is clear enough. Also, you are forgetting that MOS:RANGE doesn't have a style to exclude the upper limit as you want, nor is there a need in this case. If your only argument is that it burdens the table, then go with consensus. Jroberson108 (talk) 15:20, 9 August 2021 (UTC)

text: Please read WP:RFCBRIEF. That aside, I have never seen BMI done to more than a single decimal place.  A very brief search reveals one place seems to be the standard. BSMRD (talk) 22:56, 9 August 2021 (UTC)
replies: text: The MOS:RANGE also does not have a section of how to classify values that do not fall in any of the given ranges, so that argument is void. A fundamental requirement is that all measured values should fall in a range. Leaving a gap between ending at 24.9 (or 24.99) and beginning at 25 makes the list incomplete. On the other hand, having 25 both as end and beginning does not create overlap, since in that cases it is fully arbitrary which category is chosen, because of measurement uncertainty. A repeated more accurate measurement could break the tie. For simplicity (not necessity) one could specify all categories to be left-inclusive only. For the reader the point is to see and remember only the simple round 25, 30 etc numbers without being distracted by intervening meaningless and unnecessary 24.9 and 29.9 etc. −Woodstone (talk) 07:46, 10 August 2021 (UTC)
replies: text:  Your argument against using MOS:RANGE for a range of numbers makes no sense; a number (20) outside a range (1–10) is simply the number (20). We have ranges, so follow MOS:RANGE for each range regardless of their relations. One decimal precision is clear enough ("18.5–24.9", "25.0–29.9"). If you have a BMI with further precision (24.9999), then you naturally round it (25.0) to match the same precision of the table. There are no gaps due to the obvious precision restriction. Since ranges are inclusive, ending a range and starting the next with the same cut-off point (25) is both inacurate and a confusing overlap. I understand you don't see it that way and your intentions are to exclude the upper limits, but your intended usage is not supported by MOS:RANGE and you should discuss it further at MoS, as many editors have repeatedly said. Jroberson108 (talk) 17:42, 10 August 2021 (UTC)

text:   Thanks for taking the time to comment. Keeping it brief was difficult, but I see now the details could have been a followup post. Regarding the standard, I agree that most websites, and possibly print media, use one decimal precision. Jroberson108 (talk) 17:42, 10 August 2021 (UTC)

text: Use only one decimal, and make no mention of “rounding”.  That seems the norm.  I think typically measurements and BMI reports are only able to do one decimal.  Besides, the measurements of height/weight are not 5 digits precise, two measurements in a row might vary by a pound or quarter inch.  Having it to 3 digits is already tiny - about +/- a tenth of a percent. Cheers Markbassett (talk) 00:09, 11 August 2021 (UTC)
replies: text:  Good point about the precision of weight and height used to calculate BMI. Usually one or two decimal precision is used, but not more. A BMI with one decimal is precise enough. I also feel mentioning "After rounding." isn't needed. It was only added to console gap concerns. Jroberson108 (talk) 02:45, 11 August 2021 (UTC)

text: I believe that including any special discussion (even just a few words or mathematical symbols) is downright silly for this topic. This article is about body mass index, not mathematics. Fine details of the theory of quantization are not necessary. The above discussion of adding ("rounding to nearest 0.1") doesn't even resolve it, because the nearest 0.1 for 24.99 is 25, not 24.9, but that is clearly not what is attempted to be expressed. BMI is only a rough guide anyway, and fluctuates for everyone, and the difference is swamped by the measurement error of the weight scale and the height measurement as well. For our purposes, I think it's fine for the upper bound of one interval to be equal to the lower bound of the next interval, or to use "X.9" as an upper bound (without adding any special further explanation) if that's what authoritative sources tend to do. —⁠ ⁠BarrelProof (talk) 22:55, 13 August 2021 (UTC)
replies: text:  Thanks for your comment. If I understood correctly, you are neutral (rounded or X.9) as long as reliable sources use it, but see no need for the "After rounding" explanatory note. Jroberson108 (talk) 00:53, 14 August 2021 (UTC)
thread_title:  RfC on boundaries between categories 

message: Well, you should add more conversions if 'isolated conversion' was the problem.  Username142857 (talk) 12:24, 9 February 2022 (UTC)
replies: text: The conversion makes no sense since nobody uses that unit. It does not help any reader.−Woodstone (talk) 07:54, 10 February 2022 (UTC)
replies: text: Believe it or not, America STILL hasn't converted to metric so... Username142857 (talk) 09:15, 10 February 2022 (UTC)
replies: text: Except for BMI, which is universally metric. Can you show any sources That use these units? −Woodstone (talk) 13:54, 10 February 2022 (UTC)
replies: text: No, but it would help Americans to do less math. Having to convert your height to inches, then dividing mass by height, then having to multiply your output by 703 is harder than just dividing mass by height. Username142857 (talk) 11:54, 11 February 2022 (UTC)

text: Why is BMI universally metric? Username142857 (talk) 11:59, 11 February 2022 (UTC)

text: I agree with Woodstone that it seems unnecessary since the units are commonly metric. I haven't seen any sources that use imperial/American units. Under Body mass index#History there is info on converting it, which uses "in". Perhaps "ft" can also be added to accommodate your concerns? Jroberson108 (talk) 06:56, 11 February 2022 (UTC)
replies: text: They are useful because it is easier for Americans to calculate their BMI in lb/ft^2, so it would help them do less math! Username142857 (talk) 11:50, 11 February 2022 (UTC)

text: You just multiply by 703/144 Username142857 (talk) 11:54, 11 February 2022 (UTC)
replies: text: For a calculation in feet one would need to measure in decimal feet, not feet and inches. But anyway, the borders of the categories are given in kg/m2, so the values in lb/ft2 or lb/in2 are not useful to know. Remark also that the conversions show too many decimals and throw a very peculiar light on the gaps between the categories.−Woodstone (talk) 16:22, 11 February 2022 (UTC)
replies: text: What's a decimal foot? Username142857 (talk) 02:26, 12 February 2022 (UTC)

text: The feet and inches problem can be solved if we switch to duodecimal, or my personal favorite, senary! Using the formula lb/(ft+in/12)2 can help as well! Username142857 (talk) 02:29, 12 February 2022 (UTC)

text: That's like saying that if you know the height of a building in feet, its height in meters is not useful to know. Username142857 (talk) 02:30, 12 February 2022 (UTC)

text: I fixed the 'too many decimals' problem. And what kind of 'very peculiar light on the gaps between the categories' does it give? Username142857 (talk) 02:36, 12 February 2022 (UTC)
thread_title:  BMI imperial/american units 

message: It is much repeated that BMI is expressed in kg/m² which is scientifically not correct, it associates a weight to a surface, like for example paper thickness is associated and expressed as g/m², where this unit makes better sense, as its actual thickness is rather difficult to measure or comprehend, and as it is distributed evenly over the surface (See also Paper Thickness and Weight Explained - Action Press (action-press.co.uk)). And even with paper, you have to differentiate between types of paper (see link)
However, we are not expressing the body surface with the measurement, (look at duBois formula for that: Body Surface Area Calculator)
 but making up a number that helps us understand roughly how the relation of bodysize and bodyweight is situated, (with all its shortfalls - see body-builders BMI) this number roughly fits for adult men between 20 and 40 Years with median bodysizes, it won't fit tall or small, women, children and elderly people...
It is NOT an exact measurement. In Pediatry we use percentiles adapted for age and sex to make up for some of the shortfalls. However we should abandon the Unit for it which ist not the correct one.
I hope that this becomes clear when for example using the following Measurements for a woman: 
 body height: 161cm 
 body weight: 66.5kg
 BMI : 25.7
 Skin surface after DuBois formula: 1.7m²
In the above link (Body surface calculator) the BMI is also expressed as kg/m² with the table above quoting the surface area as 1.7m² calculating the weight of the person would be:
 1.7m² * 25.7kg/m² = 43.69kg 
which is misleading bullshit. 188.94.98.93 (talk) 10:14, 19 October 2022 (UTC)
replies: text: The units of BMI are kg/m2. This is a fact and inarguable. That area the weight is divided by is not equal to the skin surface area is irrelevant. It's also not equal to the bone, eye or teeth surface area, but that does not mean the units are anything different. 2A02:8071:680:3F00:9D5C:8CCC:E5F6:9F (talk) 14:02, 13 June 2023 (UTC)
thread_title:  Units of the BMI 

message: — Assignment last updated by Edarden1 (talk) 03:49, 28 February 2023 (UTC)
thread_title: Wiki Education assignment: Science and colonialism