The days of using the Body Mass Index (BMI) for estimating body fat seems to be coming to an end. Researchers at the Cedars-Sinai Medical Center in Los Angeles published a better method to determine how fat you are, and it's called the RFM. Using this new method you only need to know your body height and be able to measure the circumference of your waist. That's it. BMI Scientists, physicians and sometimes also trainers still use the BMI to determine if someone is too fat. In general, this method works, but in many instances, it simply does not. A better way to determine how much body fat someone has is to make DEXA scans. Measuring skin folds with clippers is a good second. But in practice, there is a need for an easier and faster way. The researchers wanted to find a simple formula that assesses the fat percentage, without having to do all sorts of difficult measurements and calculations. They used data from 12,581 Americans collected in the National Health and Nutrition Examination Survey [NHANES] to generate 365 formulas that could estimate how much fat someone has by using variables such as body weight, height, and waist circumference. The researchers then released the formulas on a database of 3,456 Americans and checked which formula gave the most accurate estimate. And the winner is... Below you see the most accurate formula: the RFM, which stands for relative fat mass. The result gives an estimate of the fat percentage. Height & waist circumference are expressed in meters, by the way. The figures below show that the RFM gives a more precise estimate of body fat percentage than the BMI does. The researchers looked at men and women, and at people from European, African and Latin American ethnicity. The RFM formula estimated the fat mass equally accurately for all groups. Conclusion "We wanted to identify a more reliable, simple and inexpensive method to assess body fat percentage without using sophisticated equipment", says lead author Orison Woolcott in a press release. [sciencedaily.com August 27, 2018] "Our results confirmed the value of our new formula in a large number of subjects: relative fat mass [RFM] is a better measure of body fatness than many indices currently used in medicine and science, including the BMI." "The relative fat mass formula has now been validated in a large database", adds research leader Richard Bergman. "It is a new index for measuring body fatness that can be easily accessible to health practitioners trying to treat overweight patients who often face serious health consequences like diabetes, high blood pressure, and heart disease." Source: Sci Rep. 2018 Jul 20;8(1):10980.
BMI is really a sad measurement. My youngest was in for his pre season physical when he was 16, and the doctor says he needs to work on his weight as his BMI was 28. I said maybe we are looking at 2 different people. You see his abs are cut and most likely his weight is muscle mass. He has calves about the same size as most people thighs and thighs that without exaggeration are tree trunks. Not to mention he is playing soccer, so he does a fair amount of cardio. The doctor is a nice guy, but he still didn't seem to see the problem with the BMI as a measure of health.
BMI is like treating the flu with leeches. I cringe everytime a "doctor" talks about BMI to gauge obesity/body fat measurements.
This is not relevant in this particular formula, as height divided by waist results in a value without unit. Asians were apparently not included.
I know it's a short summary, but in eyeballing the data, it seems that the difference in RFM errors (between male and female) is more due to heteroskedasticity rather than gender itself. They love to keep these things simple, though , so I'm sure that putting in a RFM² variable might prove statistically *significant*, but not *practically* helpful.
I have been measuring my own waist and bodyfat percentage on a weekly basis for the past 2 yrs. For me, the above formula underestimated my bf % for when i was very fat and overestimates now when I'm quite lean. Not by much however....so I would say it is of practical benefit.
The R-squared of the regression analysis does indicate a significant improvement in estimation for men versus women, probably because men carry excess fat in their stomach mostly where women store it in their hips. So it makes sense the waist measurement component does provide more accurate estimation for men. Question is if the waist means the circumference at the belly button.
That's a tough call; perhaps it's age-dependent. After a certain age, some men begin to pull their pants up to just under their armpits.