BMI Is Broken – A 2,000-Year-Old Discovery Offers a Smarter Way to Measure Body Fat

Scitech Daily ^ | March 22, 2025 | Christian Yates, University of Bath

[rarestia]

I was gonna say this. They offer displacement body mass testing in some holistic medical practices. I’ve had my BMI testing by DEXA, water displacement, and caliper test, and the results were wildly different from the BS BMI metric. Sadly, our medical system is captured by pharma and insurance companies, so doctors can only report BMI despite numbers substantially lower from more accurate tests.

[Ronaldus Magnus]

The Body Mass Index has always been a fundamentally flawed metric in that it relies on the cross-sectional area of a body instead of the total volume. Since three-dimensional bodies have three dimensions, only using the square of height instead of the cube adversely penalizes taller people.

A subject is first weighed in normal conditions and then reweighed while sitting completely submerged on an underwater chair attached to a set of scales. The differences in the dry and underwater weight measurements can then be used to calculate the buoyant force acting on the person while under water, which in turn can be used to determine their volume, given the known density of water.

This system for measuring body density is poorly designed and won't work unless the each person being measured floods their lungs with water. If they don't drown themselves, they will be able to game the system by exhaling before the test, thus reducing their buoyancy and increasing their submerged weight over someone identical who doesn't exhale. If our lungs are filled with air, we are all variably buoyant and thus, inconsistently dense. It is doubtful the inventor of this approach has ever actually tested anyone in this way.

[ViLaLuz]

He was an honorary member of the Chub Club. If he had a thicker neck he wouldn’t come up as over body fat.

[Red Badger]

He was an exercise nut so it suited him just fine. It got him out of work for two hours so he didn’t have to use his personal time after duty hours for doing exactly what they were doing.

The Navy Doctor that put him on the list said he knew he wasn’t fat but the rules didn’t have an ‘escape clause’ so there was nothing he could do!...........

[ViLaLuz]

I hope it didn’t affect his performance evaluations or physical fitness tests. If it did he should have had an alternate way to calculate BMI. But the mandatory PT was a bonus for sure.

[Red Badger]

I doubt it did. Everybody and our captain knew it was BS.............