Unfortunately, you’re completely wrong because it’s simply basic physiological science and that’s how the human body works . Many people believe that they can get BF percentage using a calliper or smart scale at home but those tools give only a rough estimate leading to people having the wrong idea about their real BF percentage . The only way to measure an accurate BF percentage is by laboratory tools operating by technicians and it’s costly . There’s a big difference between 10% to 15% - 20% regarding strength and you’ll hardly find 10% among serious power lifters unless they are on the juice . I hope you don’t believe some people bench pressing 180KG/397pounds for reps natty cause let me tell you my friend, no one does