Weight War: BMI vs BVI

Posted by Kathleen Fasanella on Oct 27, 2010 at 1:43 pm / Fit and Sizing / Trackback

There’s a weight war, did you know? The weight war will become more intense over the coming months with BVI taking center stage. So what is BVI? BVI means Body Volume Index, a measure considered to be more accurate than the more often used BMI.

Background: BMI was developed by Adolphe Quetelet over 150 years ago to measure body fat percentages. It’s a very long story but the index was effective in his day because most people were height and weight proportionate and participants of his sample data sets were homogeneous by nationality and occupation -namely soldiers (sources cite both Scottish and US soldiers so I don’t know but suspect Scottish to be more likely being that Quetelet was Flemish). These days, BMI is considered a poor alternative to measure body fat in its most common context namely that of assessing one’s health risks.

BVI isn’t the first BMI alternative (and contrary to claim wasn’t invented by Aston University but they did come up with a competing catchy acronym which as you know means everything). Another reason reason BVI may be increasingly used as a tool to measure body fat is that the technology they use (body scanners) is sexy. Okay, I’ll play it straight;  BVI will be more accurate than BMI because it computes measurements of the body beyond height and weight. [Aston U. didn’t invent that either; innumerable others like the US Navy have been doing that for years.]

If you’ve been dissatisfied with your BMI results, I’m guessing you’ll be even less satisfied with BVI based on my trial run using a variety of calculators this morning. If you’re fat under BMI, you may be even fatter under BVI. I was.

My results showed appreciable differences between BMI and BVI calculations of body fat.  Actually, there were big differences between BMI calculators period. For example, this site says I’m underweight (vanity weighing imo) and didn’t give me a percentage while another site reported my weight as normal (20.8%) but I could gain another 24 pounds and still be of “normal” weight within their reported range. Hmm. The last site I used reported my body fat percentage as 31.8% (!) meaning technically obese. I played with that calculator awhile. Either it is broken or the site is selling diet plans. I put in Sally’s measurements (she’s slender, built like a prima ballerina) and it also said she was over 30%. The summary conclusion of online BMI calculator results means you could shop around to find a percentage more to your liking. But I digress.

An official BVI calculator isn’t available online yet so I used an abbreviated calculator developed by the US Navy. I warn you the results will be painful. This calculator requires height, waist, hip and neck measurements. My score was 24.8% body fat. I think that was the most accurate result of them all. Just for grins, I put in my measures from five years ago when I knew my hydrostatic weight (the most accurate of accessible indices) and it came pretty close to it.

If you want to do the math yourself, the rough-cut BVI calculation (via) is:

Men: %BF = 495/(1.0324-0.19077(log(waist-neck))+0.15456(log(height)))-450
Women: %BF = 495/(1.29579-0.35004(log(waist+hip-neck))+0.22100(log(height)))-450

One last method used to calculate health risks -not to be confused with percentage of body fat- is the waist to hip ratio.

8 Responses to “Weight War: BMI vs BVI”

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frieda
October 27th, 2010
3:09 PM

The last site you were referring to, the one that tends to tell people they are obese, simply leaves out your height. Guess how fat I am, being 6 ft 2″, taking only my weight into account. They simply don’t expect a woman of this size.

Reader
October 27th, 2010
7:38 PM

I’m short and 106 pounds, which admittedly is a lot more than I’d like to weigh, but the second site said I’m over 32% fat, which is obese. The first site said I was 26% fat. I’ve always sensed that the BMI rating wasn’t accurate for me — at 100 pounds I’m not underweight as per the BMI — but OBESE?

Still, this makes me believe that I’m correct to try to drop some weight I’ve gained at the height of middle age. I’ve always attempted to do it through calorie reduction and exercise, including strength training.

So essentially, my instincts have been correct. I will feel free to ignore the visibly obese people who keep acting as if I’m some of anorexic.

Xochil
October 27th, 2010
8:34 PM

I tried out the body fat calculator (the one that says you were obese) and got similar results. At 5’5″ and 124lbs, it says that I have 32% body fat, and I too am “obese”. LOL, it must be broken. I even switched the option to Male instead just for kicks and it says I have 6% body fat. What a difference! I don’t think that’s accurate either though. The last one that required the neck measure and all says 24.6% body fat, which seems more accurate as well. Interesting post!

Paul
October 28th, 2010
7:35 AM

I would be wary of commercial sites, and tend toward more ‘official’ sources such as the NIH and CDC websites. The NIH site is your ‘another site’, and CDC is here: http://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/english_bmi_calculator/bmi_calculator.html, both with identical results.

But this is so darned imperfect. The calculation is the same for all adults – so my 86 year old mother is judged by the same measure as her 21-year old college student athlete grand daughter (both female, adult, equal height). Huh. And the ‘big-boned workin farmhand-gal from southern alberta’ has to measure up against the tiny little waif that was blown off her feet in yesterday’s windstorm (both female adults, same height).

Grace
October 28th, 2010
1:50 PM

I plugged in the numbers using inches and came up with a headscratcher.

I redid it in centimeters and came out 27%; a physicist should know better than
to use inches.

27% is what my Tanita body fat scale told me this morning. It measures the electrical impedance from one foot, up through the leg, torso and down the other leg. At the gym, the trainer used a hand-held device and came up with 28% going from one arm to the other. They are all in the same ballpark.

It makes sense for a sedentary desk jockey to have a higher fat measurement for the upper
body than for the legs. I walk as much as I can fit into my day.

Sabine
October 29th, 2010
12:22 PM

the first body fat calculator is bogus. I know I am overweight and just a teensy step away from obese according to the BMI (of 29), but there is not way that Kathleen in her size tiny has almost as much body fat as I in my size 10/12. mine said 32.57, so definitely obese.

the body fat calculator that’s the closest to the BVI WAS painful, lol, but then, i have a mirror and can see all my jiggles. ick

According to the Waist to Hip Ratio of 0.79 I am at low risk for fat-related health problems however, so that made me smile.

Allen
October 30th, 2010
12:49 PM

Hi (stupid guy comment warning)

BVI sounds great as boob weight is never factored in. Yes breasts do grow with weight but size and shape range wildly. Ever see a 42 A cup? She has more problems than someone looking for a 28 DD. BTW – 42B is her “girls not out” bra as it makes her look propotional. I laughed (respecfuly of course) because she has “the girls”, her boobs, out all night (and day). It is *soo* hard to find a 42 A that when one comes close the bra must be saved.

The BVI is also interesting because weight around the mid section indicates possible heart problems.

Lastly – the different light patterns used for 3-D body measurements make a great sewing guide. Drawback – no impulse buying. Think about the math behind internet & catalog shopping: “Catalog = Shopping – Ttrying It On ” [that was from the site morenewmath.com (http://www.morenewmath.com/250/catalog/)]

Marie-Christine
November 10th, 2010
4:44 AM

There is an online easy calculator for the BVI http://how-to-burn-fat.com/calculators/body-fat-index-calculator
I find interesting the latest health standard which give all men and all women the waist measurements not to overshoot. Now I know my waist is fat, that’s not the issue :-). But I’m the height of an average guy, so why should that standard apply to me as well as to say a 4’9″ woman??
Conclusion: all these measures and standards are approximations at best. As Justice Potter Stewart would say ‘you know it when you see it’ to some extent.

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