White? Muscle density is less than 4. 5g/cm3
The average muscle density of yellow race is 4. 6- 10。 8g/cm3
Black is greater than 1 1. 6g/cm3？ Similar bone density ratio?
So what? China people of the same weight? Looks shorter than Americans? Same height and thin? Watch weightlifting? Wrestling? Player? Is it obvious? As for China people who eat rice, Americans eat meat? So thin? Is that bullshit? You can tell by watching sumo wrestlers? That depends on whether you eat more or less. As for fitness, just look at Bruce Lee. He is thin, but strong.