> Many active gym people have pretty high BMIs but fairly low fat
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.
I do agree to some extent, but really the overweight threshold for BMI is 25. And 30 for obese.
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.
Going from your size to 27 means putting on 10kg of muscle. That's a beef brisket. Half the guys in the gym don't have that much more musle than you.
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.
My completely made up rule is you get an extra point for every plate you bench (or squat etc). Its not a dramatic difference. If you bench 225 you’re not overwreight till 27 BMI, which iirc used to be the actual cutoff until they narrowed it.
Obese is hard. Overweight is easy if you walk, take the stairs, do the occasional pushup, and play something like hockey once week. Source: my entire life.
N=1
But specifically, it requires no gym time. Muscle mass is built with through reps not weight, and there are lots of non-gym-rat behaviors that do that. I'm not winning any comps.
And obviously genetics matter, but it look at master level soccer players: athttps://pmc.ncbi.nlm.nih.gov/articles/PMC6239137/