ALM v. BMI

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So, we discussed obesity yesterday. And, like our (misguided) ideas about cholesterol (there’s more than just good and bad cholesterol, since some of the “bad’ should more likely be termed “benign”), we are finding out that obesity per se is not the primary issue.

And, that led me to finding another measurement about which I never heard a peep. Absolute appendicular lean mass (ALM). It’s something that has been used to predict the chance one will develop osteoporosis (in post-menopausal women), among other things.

We can’t really measure our body’s muscle mass. So, we must rely on surrogate measurement.

We can measure the amount of lean tissue in our body (using whole-body dual-energy x-ray absorptiometry [aka DXA]). This is the sum of all the lean tissue in our arms and legs. But, like obesity, most scientists use the ratio of ALM/height2 (although some use the ALM/BMI ratio) to approximate muscle mass (and to discern if there is a loss of muscle mass in the patient).

A recent article by Camila Miranda (Federal University of Triangulo Meneiro, Brazil) [coauthors VFB de Morais, FM Martins, SB Santagnello, RF de Paula, and Drs. DCS Pelet, CL Orsatti, LM Cangussu-Oliveira, and MV Campos Sousa; along with Dr. EA Petri Nahas of Sao Paolo University (Brazil)] discussed the principle, which brought it to my attention.

ALM and BMI

Actually, they were examining the difference between genders for skeletal muscle mass loss and the inconsistencies between sarcopenia and risk of bone fracture. But, this concept of knowing the amount of muscle mass actually is just as important in recognizing the differences between a healthy obese subject and one who is not (as discussed yesterday).

The above-mentioned studyset up three tiers:  Appendicular lean mass of less than 15 kg; appendicular lean mass/height2 (appendicular lean mass index) of less than 5.67 kg/m2; and a ratio between appendicular lean mass and BMI of less than 0.512, which separated those with problems from those without.

Maybe it’s time the researchers started combining both of these measurements- BMI and ALM- to discern when one’s obesity leads to poor health.

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6 thoughts on “ALM v. BMI”

  1. I’ve heard of BMI but not ALM. I think my numbers are okay, I’m not overweight and I’m still sticking to my healthy eating (okay sometimes I go for a treat!)
    Martha recently posted..My Baby Dragon

  2. Is the DXA the same as the “DEXA” scans I (as a woman in her late 60’s with risk factors for osteoporosis including one medical condition) gets every two years? I am close to osteoporosis and my gyn provider has recommended that I gain a small amount of weight to reduce my risk of osteoporosis. (My BMI is 20.4). I found that interesting, but the only result I’m given from the DEXA scan is my bone density in various areas (hips, etc.). I never even heard of ALM but that must be part of how my osteoporisis risk is calculated.
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