Alex
#41
I am a BMI of 25.7. Given I have a 12% body fat percentage, I am fine with that.
It seems to me that waist size and a couple of other measures are better in aggregate than BMI as a risk measure in many circumstances. 5 Alternatives To Body Mass Index (BMI)
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Neo
#42
Just making sure it was clear that my last point above was exactly in the spirit of brining in complementary/better measures to/than BMI.
The paper above is a Mendelian randomization study and is based on FATT mass index (and not BMI).
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I mean, how tf DO you control for confounders in BMI, given that fat-mass and muscle mass do opposite things and completely destroy the signal. It’s only that so much of the Western world is so unhealthy that you even have these associations. If there was only a way to go back into all the data and magically parcel out, but no, data is too messy.
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You control for it by using a mirror. If you are shredded, no need to worry about BMI.
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Not to be a simp for Ryan Masters, but a lot of these questions are answered in the paper at the top of the thread.
Fat mass and muscle mass affect body shape differently, the NHANES data included an impressive amount of body shape measurements for its participants, and he controlled for them. The size of your waist, your thighs, your hips. Skin-fold measurements (a good marker for adiposity) in various parts of your arms and legs.
When you control for that, there is still a BMI effect on mortality. That is, even if you are shredded, it is worthwhile to think about BMI.
As for the paper @Neo shared, I don’t find the headline result particularly surprising (that genetically-determined adiposity is bad for you), but I do find that the J shaped curve in the general American populace that reduces to a linear curve when you control for lifestyle adds credence to the notion that being skinny is only good if you’re taking care of yourself! If you’re skinny and not engaging in healthy behaviors… perhaps a bad omen.
As for it being complimentary to/better than BMI, one thing the Masters paper didn’t really talk about was how much of the variance in risk can be determined by BMI, once you’ve controlled for everything else. He reported hazard ratios and error bars for different BMI ranges, which is good, but he had all the data he needed to similarly report the effects of adiposity. If you go through the crosstabs like I did at the top of the thread, it’s clear that the ABSI index is high-yield and that fits the existing literature but yea.
I think it’s clear that it’s less about being shredded, it’s more about being within a healthy weight range (pick the hazard ratio in the Masters paper you’re comfortable with; 20% is like… fine imo) and maintaining a low level of adiposity, with a preference for a smaller waist and stronger legs.
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