I think this is greatly exhaggerated.
Yeah you can put on as much muscle as Arnold and have a FFMI of about 27 then maybe have a BMI of 34 if you have 20% body fat.
But a very gifted natty might cap out at maybe 24 with a BMI of 30 at 20% bodyfat. But let's be realistic. This is not "many active gym people". This is the guy winning the local strongman meet.
Yes a couple of years training for most people can add a couple of points to BMI but I think people exaggerate how much this is. Go look at a 20lb brisket at costco - you don't see people with that much extra muscle all that often.
At 6 feet / 183 cm that it takes 184 lbs / 83 kg to be overweight. From what I could find, for regular gymgoers the typical weight for people around 6feet is 180-190lbs, which put many people around the overweight threshold. I am myself at 24.9, and while not skinny I am definitely in the skinnier half of the people at my local gym.
Yeah really well muscled guy being BMI 27 is probably ok but by 30 it's not natural muscles that are making the scales go up.
And obviously genetics matter, but it look at master level soccer players: athttps://pmc.ncbi.nlm.nih.gov/articles/PMC6239137/
I’ve been in the overweight BMI category with low body fat by being active at the gym and focusing on diet. It takes some work to get there.
If I check the calculators for the obese BMI range, there was no way I could get there without either gaining a lot of fat on top of the muscle. The amount of muscle required to have an obese BMI with healthy amount of fat is absurd.
E.g. 20% bodyfat at 250lbs is still a lot of fat.
Of course it's difficult to ever get very high on absolute fat if at 15% or below.
Additional muscle is positive for health, but only up to some reasonable threshold. There is no health benefit to having very high levels of muscle, and in fact it may be negative for your health at extreme levels. E.g. many bodybuilders have trouble breathing, sleep apnea etc.
Both people in the example have 60lbs of fat. 1lb of muscle doesn't cancel out the negative health effect of 1lb of fat
It’s not the fat that kills. It’s oxidated lipids that kill.
1. https://www.cdc.gov/nchs/data/series/sr_03/sr03-046-508.pdf
As for 2, men in the US are getting shorter because of immigration which adds many confounders.
https://medlineplus.gov/ency/article/003998.htm
"People typically lose almost one-half inch (about 1 centimeter) every 10 years after age 40. Height loss is even more rapid after age 70. You may lose a total of 1 to 3 inches (2.5 to 7.5 centimeters) in height as you age."
So people DO in fact tend to lose about 2 inches at age 80 versus their younger selves.